







































FI Abam et al. /Future Technology                                                                                         February 2024| Volume 03 | Issue 01 | Pages 
40-55 

40 

 

 

 

Article 

Thermodynamic and environmental performance 

of a Kalina-based multigeneration cycle with 

biomass ancillary firing for power, water and 

hydrogen production 
Fidelis I. Abam1*, Victor Umeh2, Ekwe Bassey Ekwe3, Samuel O. Effiom4, Jerome Egbe5, Adie J. 

Anyandi4, James Enyia4, Ugwu Hyginus Ubauike2, Macmanus C. Ndukwu6 

1Energy, Exergy and Environment Research Group (EEERG), Department of Mechanical Engineering, University of Calabar, 

Nigeria 
2Department of Mechanical Engineering, Michael Okpara University of Agriculture Umudike, Nigeria 
3Department of Mechanical Engineering, Covenant University Ota, Nigeria 
4Department of Mechanical Engineering University of Cross River State, Calabar, Nigeria 
5Department of Civil and Environmental Engineering, University of Cross River State, Calabar, Nigeria 
6Department of Agricultural and Bioresources Engineering, Michael Okpara University of Agriculture Umudike, Nigeria 

A R T I C L E   I N F O 
 

Article history: 
Received 19 April 2023  
Received in revised form 
02 June 2023 
Accepted 20 June 2023 
 
Keywords:  
Energy, Exergy, Kalina cycle, Sustainability, 
Hydrogen 
  
*Corresponding author 
Email address: 
fidelisabam@unical.edu.ng 
 
 
DOI: 10.55670/fpll.futech.3.1.5 
 

A B S T R A C T 
 

The performance of a Kalina-based multigeneration cycle for power, water, and 
hydrogen production is investigated from thermo-environmental, 
sustainability, and thermo-economic perspectives. The plant comprises a gas 
turbine (GT), Kalina cycle (KC), and vapor absorption system (VAS) as the 
bottoming cycle and an integrated domestic water heater and proton-electron 
membrane (PEM) electrolyzer for hydrogen production. The system's models 
were simulated with Engineering Equation Solver (EES) codes. The results 
indicate a net energy efficiency of 53.48% and exergy efficiencies of 50.05 %, 
with an additional 30,178 kW of products from the bottoming cycles. The GT 
contributed approximately 85.81 % of the overall exergy destruction. The 
system's exergo-thermal index (ETI) stood at 1.713, with the GT only having an 
ETI of 2.106. Similarly, the exergetic sustainability index (ESI) of the 
multigeneration plant was not greater than 2.04. The exergoeconomic analysis 
shows a low average energy cost from the GT, estimated at 0.836 $/GJ, 
compared to the Kalina subsystem, which stood at 6.53 $/GJ. The 
thermodynamic and cost evaluation of the system demonstrates substantial 
benefits from the plant, which kept the hydrogen production rate at 0.1524 
kg/hr. 

 

1. Introduction 

The role of energy availability in economic development 
cannot be over-emphasized. Energy remains the fulcrum for 
sustainable development [1]. For the past decades, the 
fundamental processes for energy generation, especially 
electricity, have been from burning fossil fuels in gas turbine 
plants, steam plants, and a combination of the two in 
cogeneration [2, 3]. Several plant configurations have been 
developed and implemented to increase these thermal plants' 
energy efficiency. Research is increasing to produce different 
products from these systems, which has increased in scope in 

recent times [4, 5].  However, the configuration of the lower 
bottoming cycles and the choice of operating parameters play 
vital roles in developing sustainable products with minimal 
exergy destruction and environmental impact. Among the 
many options for lower bottoming cycles to increase energy 
conversion system products are the organic Rankine cycle 
(ORC) [6-8],  Kalina cycle [9, 10], Goswam cycle [11]  steam 
turbine cycle [12], and for water electrolyzers [13]. 
Multigeneration plants have been presented in the literature. 
For example, Dev and Attri [12] presented a Multi-plant cycle 
based on ORC, which produces six products: electricity, 

 

 

Future Technology 

Open Access Journal 

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February 2024| Volume 03 | Issue 01 | Pages 40-55 

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ISSN 2832-0379 

mailto:fidelisabam@unical.edu.ng
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FI Abam et al. /Future Technology                                                                                         February 2024| Volume 03 | Issue 01 | Pages 40-55 

41 

 

heating, hot water, hydrogen, cooling, and dry air. The results 
indicate an energetic coefficient of performance (COP) of 
approximately 60%, while that for the exergetic COP was 
estimated at 10%. Similarly, the study in reference [13] 
presented a primary Brayton cycle with several strings of 
bottoming cycles that can provide electrical power, domestic 
water heating, and cooling through refrigeration processes 
embedded in ORC and vapor absorption cycles. The study 
obtained energy and exergy efficiencies of 44.22 and 61.50 %, 
respectively, with an exergo thermal index of 0.675. 
Additionally, other lower cycles are reported to produce 
hydrogen, while some are used for the desalination of water 
[14, 15]. The study in [14] proposed a multi-cycle power plant 
for cooling, heating, and desalting water production. The 
result shows that the water production rate was 0.364 kg/s 
with a cooling rate and power output estimated at 1 MW and 
30.5 MW, respectively. Similarly, Abam et al. [15] designed 
and developed a novel incorporated cycle based on the solid-
oxide fuel cell-GT for concurrent fresh water, electricity, and 
hydrogen production. The exergetic efficiency was estimated 
at 54.2 % at refresh water rate production of 90.1 m3/h at a 
unit cost of 32.9 $/GJ. Furthermore, Anvari et al. [16] analyzed 
an innovative solar-based multigeneration plant. The system 
was developed for power generation, desalination, and 
hydrogen production. The thermodynamic assessment 
indicates that the multigeneration system had 23.2 % as 
energy efficiency and 6.2% for exergy efficiency. Ref [17] 
performed a thermodynamic and economic evaluation of a 
geothermal-based integrated plant which comprises ORC, 
domestic water heater, electrolyzer, and absorption 
refrigeration system to produce hydrogen and electricity, 
heating and cooling. The total efficiencies were estimated at 
34.98% energy and 49.17% exergy, whereas the hydrogen 
production rate and unit cost of production stood at 0.052 g/s 
and 5.967 $/kg, respectively. Furthermore, Khalid et al. [18] 
presented a techno-economic valuation of a solar, 
geothermal-driven multigeneration system to produce; 
electricity cooling, hot water, heating, and hydrogen. The 
hydrogen production rate was estimated at 2.7 kg/h while $ 
476,000 and $ 0.089/kWh were the net presents and the 
levelized cost of electricity. Ref [19] proposed a geothermal 
multigeneration plant comprising an electrolyzer, absorption 
cycle, Kalina, and flash cycles for hydrogen and ice 
production. The results show a maximum exergy efficiency of 
26.25%. Multigeneration systems require adding bottoming 
cycles to gas-fired, geothermal, or solar-based topping cycles 
to generate multiple products. Thus, several choices on the 
mode of a bottoming cycle depend on several factors. These 
may include the exiting temperature of the topping cycle flue 
gas, the required efficiency, the quantity of desired products, 
and the economic and environmental impact of the bottoming 
cycle.  The Kalina cycle can provide an efficiency gain of 10-50 
% compared to the conventional thermodynamic cycles with 
equivalent output. However, system modification or 
adjustment in the thermodynamic pathways may be 
necessary to maximize the waste heat used in the bottoming 
cycles. The current study introduced a dual heat input to 
improve the thermal heat requirement of the PEM 
electrolyzer from the same energy source. The latter will 
increase the hydrogen production yield since hydrogen 
production yield is related to the quantity of electricity and 
heat in the PEM electrolyzer. An external thermal heat source 
for the electrolyzer may increase system costs and 
maintenance procedures. In the current study, an external 
heat source for the electrolyzer was avoided. The system was 
designed to utilize the dual heat input from the condensate of 

the two Kalina condensers. The latter innovation improved 
the hydrogen production yield and reduced the 
multigeneration plant's economic cost. In light of this 
development, this research proposes a modified Kalina-based 
multigeneration cycle incorporating biomass gasification for 
reheating in the combined topping cycle. The study thus 
determines the thermo-environmental and thermo-economic 
performance of the modified Kalina-based multigeneration 
cycle. The best operating parameters corresponding to low 
operating costs and environmental impact were equally 
evaluated. 

2. System description 

The operation starts at state (1) in Figure 1, where the air 

is drawn to the low-pressure compressor (LPC), and the 

temperature and pressure are raised to state (2). An 

intercooler reduces the mechanical work required for 

compression from the state (2) to (3). The cooled air is 

recompressed by a high-pressure compressor (HPC) at state 

(3). The compressed air is heated partly by an expanded gas 

from the low-pressure turbine (LPT). Fuel is added to the 

combustion chamber (CC) at constant pressure, raising the 

energy level of the air stream to the high-pressure turbine 

(HPT), which expands to a pressure sufficient to drive both 

the HPC and LPC. The expanded gas is reheated with biomass 

gas for expansion in the LPT to produce shaft work which 

drives an alternator to produce electricity. After partly raising 

the air temperature in a heat exchanger, the expanded gas is 

made to pass through a vapor generator which powers the 

Kalina cycle embedded with a vapor absorption system (VAS). 

Ammonium water and lithium bromide drive the Kalina and 

VAS system, respectively. In the Kalina cycle, after the 

ammonia water solution receives heat, the energy level of the 

mixture increases at the state (17). The separator is provided 

to separate the ammonium water solution into rich and weak 

solutions. The rich solution expands in the turbine producing 

electrical energy. The expanded vapor, still rich, is further 

separated in another separating vessel. The rich part of the 

mixture is condensed and throttled, and evaporated, 

providing cooling in the first part of this cycle. Meanwhile, the 

weak solution already expanded in the turbine and separated 

is throttled to a pressure equal to the weak solution at state 

(24) and mixes with the hot vapor leaving at state (23) after 

being equally throttled. These two streams heat the desorber 

for powering the VAS. The exiting stream at the desorber is 

passed through a heat exchanger before being added up with 

the resulting stream used for refrigeration at state (31). The 

summation produces a stream at state (32), which passes 

through a heat exchanger and condenser and is finally 

pumped to the vapor generator to commence the next cycle. 

The heat obtained from the dual condensation of the 

expanded refrigerants in the Kalina cycle is used to heat the 

water directed for electrolysis in the PEM electrolyzer. Part of 

the electricity generated from the Kalina turbine is utilized for 

the electrolyser's operation to produce hydrogen. 

3. Methodology and system modelling 

3.1 Thermodynamic modelling 

The general energy flow balances in a thermodynamic 

system under steady for the kth component are presented in 

Eq (1) [20, 21]. 

 



FI Abam et al. /Future Technology                                                                                         February 2024| Volume 03 | Issue 01 | Pages 40-55 

42 

 

 

Figure 1. Schematic of the multigeneration plant 

 

∑ �̇�𝑘 + ∑ �̇�𝑖 (ℎ1 +
𝐶𝑖

2

2
+ 𝑔𝑧1) = ∑ �̇�𝑒 (ℎ𝑒 +

𝐶0
2

2
+ 𝑔𝑧2) +

 ∑ 𝑊                    (1) 

The general exergy balance for a control volume in a steady 
state, neglecting potential, kinetic, and electrical energy, is 
defined as: 

�̇�𝑥𝑑 = ∑ (1 −
𝑇0

𝑇𝑘
)𝑘 �̇�𝑘 − �̇�𝑐𝑣 + ∑ (𝑛𝑖�̇�𝑥𝑖) − ∑ (𝑛𝑒𝐸�̇�𝑒)𝑒𝑖          (2) 

Where �̇�𝑥𝑑 is the exergy destruction rate, (1 −
𝑇0

𝑇𝑘
) �̇�𝑘 is the 

exergy flow rate accompanying heat transfer, �̇�𝑐𝑣 is the rate 
of work done within the control volume, 𝑛𝑖�̇�𝑥𝑖  and 𝑛𝑒𝐸�̇�𝑒 is 
the exergy flow rate in and out of the control volume. Exergy 
destruction is expressed in terms of product and fuel for a 
specific component.  

�̇�𝐷,𝑘 = �̇�𝐹,𝑘 − �̇�𝑃𝑘−�̇�𝐿,𝑘            (3) 

The exergy efficiency,𝜓𝑘, and the exergy destruction ratio is 
equally defined for the kth component as: 

𝜓𝑘 =
�̇�𝑃𝑘

�̇�𝐹,𝑘
                                                     (4) 

 

 

 

𝑌𝐷,𝑘 =
�̇�𝐷,𝑘

�̇�𝐹,𝑡𝑜𝑡𝑎𝑙
            (5)

    

Furthermore, Eqs (1) to (5) were applied to Figure 1 to derive 
the energy quantities for the system presented in Table 1 in 
Appendix. 

3.1.1 Exergoeconomic modeling  
 The components’ purchase and equipment cost (PEC) 

are written as functions of their operating parameters. The 

general cost balance for a control volume for the  𝑘𝑡ℎ 

component is presented [21]. 

 �̇�𝑞,𝑘 + ∑ �̇�𝑖,𝑘𝑖 + �̇�𝑘 =  ∑ �̇�𝑒,𝑘𝑒 +  �̇�𝑤,𝑘           (6) 

Where �̇�𝑞,𝑘 , is the cost associated with the 𝑗𝑡ℎ  sum of exergy 

streams to the system’s 𝑘𝑡ℎ, ∑ �̇�𝑖,𝑘𝑖 , is the levelized cost rate 

for the 𝑘𝑡ℎ component, �̇�𝑘. The cost associated with the 𝑗𝑡ℎ  
sum of exergy streams from the system’s 𝑘𝑡ℎ component 

is ∑ �̇�𝑒,𝑘𝑒 , while the work associated with the 𝑘𝑡ℎ component 

in the system is denoted with the term �̇�𝑤,𝑘.  

The cost of the 𝑗𝑡ℎ  stream is related to the cost of specific cost 
and the exergy, work, or heat with the relationships:  



FI Abam et al. /Future Technology                                                                                         February 2024| Volume 03 | Issue 01 | Pages 40-55 

43 

 

�̇�𝑗 =  𝑐𝑗�̇�𝑥𝑗             (7) 

�̇�𝑤,𝑘 =  𝑐𝑤�̇�            (8) 

�̇�𝑞,𝑘 =  𝑐𝑞�̇�            (9) 

The cost rate �̇�𝑘  for the components is present as: 

�̇�𝑘 =  
𝑃𝐸𝐶𝐹×𝐶𝑅𝐹×𝜙

𝑁×3600
         (10) 

PECF, CRF, and 𝜙 represent the purchase of equipment cost 
function, capital recovery factor, and maintenance factor, 
respectively. The system’s annual operational hours are 
denoted with N while the capital recovery factor is expressed: 

𝐶𝑅𝐹 =  
𝑖|1+𝑖|𝑛

|1+𝑖|𝑛−1
          (11) 

Where n is the estimated plant life in years, another exergy-
related index is the cost of exergy of product and fuel for the 
component. A detailed description of the component cost of 
fuel and product is found in [22]. The general relationship for 
evaluating the specific cost of a product for the kth 
component 𝑐𝑃,𝑘  ($/𝑘𝐽), and that of fuel 𝑐𝐹,𝑘  ($/𝑘𝐽), as well as 

the exergoeconomic factor, 𝑓 is presented in Eqs (12) – (14), 
respectively.  

𝑐𝑃,𝑘  ($/𝑘𝐽) =  
�̇�𝑃,𝑘

�̇�𝑃,𝑘
         (12) 

𝑐𝐹,𝑘  ($/𝑘𝐽) =  
�̇�𝐹,𝑘

�̇�𝐹,𝑘
         (13) 

𝑓 =  
�̇�𝑘

�̇�𝑘+ �̇�𝐷,𝑘
           (14) 

The cost of exergy destruction is expressed in Eq (15). A 
summary of the cost-related terms for Figure 1 is presented 
in Table 2, while the PEC for the plant components is shown 
in Table 3.  

�̇�𝐷,𝑘 = 𝑐𝑃,𝑘𝐸𝐷,𝑘            (15) 

 
3.2 Thermoenvironmental analysis 

The environmental effect is evaluated by approximating 

the measure of pollutants produced by the plant. These 

include nitrogen oxide, �̇�𝑁𝑂𝑥 (kg/s), CO2, �̇�𝐶𝑂2
 (kg/s) and CO, 

�̇�𝐶𝑂  (kg/s). The quantity of these emissions produced and 

their production rates depend on the following indices: 

retention time, τ (s), combustion chamber pressure drop, 

∆𝑃𝐶𝐶 (kPa), adiabatic flame temperature, 𝑇𝑝𝑧  presented [23, 

24]. Consequently, the emission rates of production and the 

harmful emission factor𝐹𝐸𝐹, are defined in Eqs (16) to (20).  

�̇�𝑁𝑂𝑥
=

1.5×1015𝜏0.5𝑒−(7110 𝑇𝑝𝑧⁄ )

𝑃6
0.05(

Δ𝑃𝐶𝐶

𝑃6
)

0.5         (16) 

�̇�𝐶𝑂 =
1.79×108𝜏0.5𝑒(7800 𝑇𝑝𝑧⁄ )

𝑃6
0.05𝜏(

Δ𝑃𝐶𝐶

𝑃6
)

0.5         (17) 

�̇�𝐶𝑂2
= 𝑦𝐶𝑂2�̇�𝑔 (

�̅�𝐶𝑂2

�̇�𝑔
)         (18) 

𝑐𝑜2,𝑠𝑝 = 3600 (
�̇�𝐶𝑂2

�̇�𝑛𝑒𝑡
)         (19) 

𝐹𝐸𝐹 =
�̇�𝑁𝑂𝑥+�̇�𝐶𝑂+�̇�𝐶𝑂2

�̇�𝑔
         (20) 

Where 𝐶𝑂2,𝑠𝑝(𝑘𝑔𝐶𝑂2/𝑀𝑊ℎ) describes the amount and the 

specific 𝐶𝑂2 emissions. Similarly, �̇�𝑔, �̅� , 𝑦𝐶𝑂2 and �̅�𝐶𝑂2
 are 

the rate of mass flow of flue gas, flue gas molar mass, mass 
fraction and the 𝐶𝑂2 molar mass. The adiabatic flame 
temperature 𝑇𝑝𝑧 is defined by Eq (21). All parameters, 

constants and the terms x, y and z in Eq (21) are estimated 
according to the procedure in [24]. 

𝑇𝑝𝑧 = 𝐴𝜎𝛼exp[ 𝛽(𝜎 + 𝜆)2]𝜋𝑥∗
𝜃𝑦∗

𝜓𝑧∗
       (21)

  

3.3 Sustainability indicator  

3.3.1 The exergetic utility index  
The exergetic utility index (EUI) is depicted in Eq (22) 

and measures the extent of exergy resource utilization in a 

system regarding the same system's net output. It is a function 

of combustion efficiency,𝜆𝐶𝐶 , net output,�̇�𝑛𝑒𝑡 , exergy input, 

�̇�𝑥𝑖𝑛  and the exergy efflux to the environment, �̇�𝑥𝑜𝑢𝑡 [15].  

𝐸𝑈𝐼 =  
𝜆𝐶𝐶×�̇�𝑛𝑒𝑡

�̇�𝑥𝑖𝑛−�̇�𝑥𝑜𝑢𝑡
         (22) 

3.3.2 Exergo-thermal index 
The exergo-thermal index (ETI) measures the thermal 

impact of the system on the environment during the energy 

conversion process. Low values of ETI are desired and can be 

achieved by continuously utilizing high-temperature flue gas 

from energy conversion systems in powering other low-heat 

bottoming cycles, expressed as: 

𝐸𝑇𝐼 =  
𝐸𝑈𝐼

ℑ
  =  

𝜆𝐶𝐶×�̇�𝑛𝑒𝑡

(�̇�𝑥𝑖𝑛−�̇�𝑥𝑜𝑢𝑡)
×

1

𝛶
       (23) 

Where 𝛶 denotes the enviro-thermal conservation factor, 
expressed as: 

Υ =  
𝑇0

𝑇𝑓
           (24) 

Where 𝑇0 is the ambient temperature and 𝑇𝑓 is the 

temperature of the flue gas. 

3.3.3 Exergetic sustainability index 
The exergetic sustainability index (ESI) compares the 

magnitudes of a system’s net product to its exergy 

destruction. A system with ESI less than unity underutilizes 

the exergy resources, and it is not desirable. Conversely, a 

system with ESI greater than unity is desirable as its net 

output exceeds the total exergy destruction. The ESI is 

expressed by [25].   

𝐸𝑆𝐼 =  
𝑊𝑁𝑒𝑡

�̇�𝐷,𝑇𝑜𝑡𝑎𝑙
          (25)

  

4. Results and discussion 

4.1 Thermodynamic properties and operating 

conditions 

The simulation results of the system were obtained using 

a developed computer code written in EES. The initial 

operating conditions are presented in Table 4. The model 

development was built on the succeeding assumptions: the 

surrounding temperature and pressure exist at 25 oC and 

1.013 bar, respectively. The system and its subcomponents 

were evaluated at steady-state conditions. Pressure and 

temperature variations were neglected. The system's 

boundaries were treated as adiabatic. The working fluid for 

the Kalina system is ammonium water solution at 0.28. 

Likewise, the properties of the system, including the enthalpy 

and exergy flow rates used to calculate system performance, 

are shown in Table 5. 



FI Abam et al. /Future Technology                                                                                         February 2024| Volume 03 | Issue 01 | Pages 40-55 

44 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

4.2 Performance analysis of the system based on 

operating data 

The performance indices considered for the study are 

presented in Table 6. The system net energy and exergy 

efficiency was calculated at 53.48 and 50.05 %, respectively. 

The multigeneration system improved the topping cycle by 

19.03 and 2.58 % in energy and exergy efficiencies, 

respectively. The improvement was ascribed to the added 

products from the bottoming cycles estimated at 30,178 kW. 

These additional products include the power generated from 

the Kalina turbine, VAS and Kalina system cooling, and the 

quantity of hot water produced from the domestic water 

heater. The net power from the topping cycle stood at 55.605 

MW. Also, the system hydrogen production rate stood at 

0.1524 kg/h, with about 3498 kW of cooling and a coefficient 

of performance of 4.304. 

4.3 Component exergy destruction (ED) rates 

The system components' ED rates are shown in Table 7. 
About 85.81 % of EDs were from the GT topping cycle due to 
significant ED rates around the combustion chamber (CC). 
The GT CC and reheater contributed approximately 54.65 and 
22.57 % of the ED, respectively, to the total ED. The main 
reason for the large ED in the CC is the large temperature 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

difference between the combustion gases and the hot air. 
Using alternative preheated fuels before combustion will 
reduce ED in the CC. In the present study, operating the 
reheater with biomass syngas at 154 oC reduced ED by nearly 
25 %. Furthermore, with the integration of the bottoming 
cycles, about 15089.77 kW ED was avoided, equivalent to 
14.19 % of the total ED. Also, an additional product of 30178 
kW was achieved, which increased the exergetic 
sustainability of the bottoming cycle to approximately 1.99. 
The latter validates retrofitting the topping cycle, the Kalina 
and VAS cycles. 

4.4 Exergoeconomic parameters of the plant 

The values of the initial investment, monetary flow rate 
and levelized capital cost (LECC) rate are shown in Table 8. 
The GT HPT has the highest levelized cost per hour, calculated 
at 41.5 $/hr, followed by GT LPT and GT LPC, estimated at 
34.19 and 12.17 $/hr, respectively.  Similarly, the 
exergoeconomic parameters of the subsystems are depicted 
in Tables 9-12. From Table 9, the combustion chamber and 
reheater contribute about 39.903 and 20.613 $/hr to the total 
ED cost calculated at 106.4 $.hr. The CC and reheater have the 
least exergoeconomic factors of 0.112 and 0.279, respectively. 
One method to reduce ED cost in the CC is to improve 
combustion efficiency and reduce the temperature difference 

Table 2. Component cost and auxiliary equations for the multigeneration plant 

Component Exergoeconomic balance Auxiliary equation 
GT LPC �̇�1 + �̇��̇�𝐿𝑃𝐶

+ �̇�𝐿𝑃𝐶 =  �̇�2 Nil 

GT intercooler �̇�2 + �̇�48 + �̇�𝐼𝑁𝑇 =  �̇�3 + �̇�49 �̇�2�̇�3 −  �̇�3𝐸2 = 0 
GT HPC �̇�3 + �̇��̇�𝐻𝑃𝐶

+ �̇�𝐻𝑃𝐶 =  �̇�4 Nil 

GT Hex �̇�4 + �̇�11 +  �̇�𝐻𝐸𝑋 =  �̇�5 + �̇�12 �̇�11�̇�12 −  �̇�12𝐸11 = 0 
GT CC �̇�5 + �̇�6 + �̇�  𝐶𝐶  =  �̇�7 Nil 
GT HPT  �̇�7 + �̇�  𝐻𝑃𝑇  =  �̇�8 + �̇��̇�𝐻𝑃𝐶

+ �̇��̇�𝐿𝑃𝐶
 �̇�7�̇�8 −  �̇�8𝐸7 = 0 

�̇��̇�𝐿𝑃𝐶
�̇�𝐻𝑃𝐶 − �̇��̇�𝐻𝑃𝐶

�̇�𝐿𝑃𝐶 = 0 

GT REH �̇�8 + �̇�9 +  �̇�  𝐻𝑃𝑇  =  �̇�10 Nil 
GT LPT  �̇�10 + �̇�  𝐿𝑃𝑇  =  �̇�11 + �̇��̇�𝐿𝑃𝑇

 �̇�10�̇�11 −  �̇�11𝐸10 = 0 

Kal. Vap Gen. �̇�12 + �̇�37 + �̇�𝑉𝐺 =  �̇�13 + �̇�17 �̇�12�̇�13 −  �̇�13𝐸12 = 0 
Kal. Sep 1 �̇�17 + �̇�𝑆𝐸𝑃1 =  �̇�18 + �̇�22 �̇�18�̇�22 − �̇�22𝐸18 = 0 

Kal. Valve 1 �̇�22 +  �̇�𝑉1 =  �̇�23 Nil 

Kal. Valve 2 �̇�21 +  �̇�𝑉2 =  �̇�24 Nil 

Kal. Turb. �̇�18 + 𝑍𝐾𝑎𝑙̇ 𝑇𝑢𝑟𝑏
=  �̇�20 + �̇�𝑊𝐾𝑎𝑙̇

𝑇𝑢𝑟𝑏
+ �̇��̇�𝑃𝑢𝑚𝑝1

 �̇�18�̇�20 − �̇�20𝐸18 = 0 

�̇�𝑊𝐾𝑎𝑙̇
𝑇𝑢𝑟𝑏

�̇�𝑃𝑢𝑚𝑝1
− �̇��̇�𝑃𝑢𝑚𝑝1

𝑊𝐾𝑎𝑙̇ 𝑇𝑢𝑟𝑏
= 0 

Kal. Sep 2 �̇�20 +  �̇�𝑆𝐸𝑃2 =  �̇�21 + �̇�28 �̇�21�̇�28 −  �̇�28𝐸21 = 0 

Kal. CND 1 �̇�28 +  �̇�59 + �̇�𝐶𝑁𝐷1 =  �̇�29 + �̇�60 �̇�28�̇�29 − �̇�29𝐸28 = 0 
Kal. Valve 3 �̇�29 +  �̇�𝑉3 =  �̇�30 Nil 

Kal. Evap 1 �̇�30 +  �̇�67 +  �̇�𝐸𝑉𝑃 =  �̇�31 + �̇�68 �̇�67�̇�68 −  �̇�68𝐸67 = 0 
Kal. HEX 1 �̇�26 +  �̇�36 +  �̇�𝐻𝐸𝑋 =  �̇�27 + �̇�37 �̇�26�̇�27 −  �̇�27𝐸26 = 0 
Kal. HEX 2 �̇�32 +  �̇�35 +  �̇�𝐻𝐸𝑋 =  �̇�33 + �̇�36 �̇�32�̇�33 −  �̇�33𝐸32 = 0 
Kal. CND 2 �̇�33 +  �̇�57 +  �̇�𝐶𝑁𝐷2 =  �̇�34 + �̇�58 �̇�33�̇�34 −  �̇�34𝐸33 = 0 
Kal. Pump 1 �̇�34 +  �̇��̇�𝑃𝑢𝑚𝑝1

+ 𝑍𝑃𝑢𝑚𝑝̇ 1
=  �̇�35 Nil 

VAS desorber �̇�25 +  �̇�44 +  �̇�𝐷𝐸𝑆𝐵 =  �̇�26 + �̇�38 + �̇�45 �̇�25�̇�26 −  �̇�26𝐸25 = 0 
�̇�38�̇�45 −  �̇�45𝐸38 = 0 

VAS HEX 3 �̇�43 +  �̇�45 +  �̇�𝐻𝐸𝑋 =  �̇�44 + �̇�46 �̇�45�̇�46 −  �̇�46𝐸45 = 0 
VAS Valve 4 �̇�39 +  �̇�𝑉4 =  �̇�40 Nil 

VAS Pump 2 �̇�42 +  �̇��̇�𝑃𝑢𝑚𝑝2
+ �̇�𝑃𝑢𝑚𝑝2 =  �̇�43 Nil 

VAS Absorber �̇�41 +  �̇�47 + �̇�65 +  �̇�𝐴𝐵𝑆𝐵 =  �̇�42 + �̇�66 |�̇�66 − �̇�65| ∗ �̇�42 −  �̇�42 ∗ |�̇�66 − �̇�65| = 0 

VAS EVP 2 �̇�40 +  �̇�63 +  �̇�𝐸𝑉𝑃 =  �̇�41 + �̇�64 �̇�63�̇�64 −  �̇�64𝐸63 = 0 
VAS Valve 5 �̇�46 +  �̇�𝑉5 =  �̇�47 Nil 

VAS CND 3 �̇�38 +  �̇�61 +  �̇�𝐶𝑁𝐷3 =  �̇�39 + �̇�62 �̇�38�̇�39 − �̇�39𝐸38 = 0 
Water heater �̇�13 + �̇�15 +  �̇�𝑊𝐻 =  �̇�14 + �̇�16 �̇�13�̇�14 −  �̇�14𝐸13 = 0 
PEM Electrolyser �̇�52 +  �̇�19 + �̇�𝐸𝐿𝐸𝐶𝑇𝑅. =  �̇�53 + �̇�54 |�̇�52 + �̇�19||�̇�53 + �̇�54| −  |�̇�53 + �̇�54||�̇�52 + �̇�19| = 0 

PEM Hex �̇�58 +  �̇�60 + �̇�50 +  �̇�𝐻𝐸𝑋 =  �̇�51 + �̇�69 |�̇�58 + �̇�60| ∗ �̇�69 − �̇�69 ∗ |�̇�58 + �̇�60| = 0 

PEM O2 separator �̇�54 +  �̇�𝑂𝑥𝑦𝑔𝑒𝑛𝑆𝑒𝑝 =  �̇�55 + �̇�56 �̇�55�̇�56 −  �̇�56𝐸55 = 0 

 
 



FI Abam et al. /Future Technology                                                                                         February 2024| Volume 03 | Issue 01 | Pages 40-55 

45 

 

between the working fluid and combustion fuel. However, 
this can be achieved by firing the CC with preheated fuel. In 
the Kalina subsystem (Table 10), the vapour generator (VG) 
cost improvement potential is primarily dependent on the 
equipment cost rates than the cost due to ED.  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Subsequently, since the VG cost is directly linked to the 
quantity of heat transfer, the choice of working fluid and 
efficient design of the heat transfer area is germane in 
reducing the cost of the system components.  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table 3. Component cost functions, cost of product and cost of fuel [15, 18, 22] 

Component Cost function  

[$] 

Cost of product Cost of fuel 

GT LPC 39.5�̇�2

0.9 − 𝜂𝐿𝑃𝐶

|
𝑃2

𝑃1

| 𝑙𝑛 |
𝑃2

𝑃1

| 
�̇�2 − �̇�1 𝑥. �̇�𝐻𝑃𝑇 

GT intercooler 
130 |

𝐴𝐼𝑁𝑇

0.093
|

0.78

 
�̇�49 − �̇�48 �̇�2 − �̇�3 

GT HPC 39.5�̇�4

0.9 − 𝜂𝐻𝑃𝐶

|
𝑃4

𝑃3

| 𝑙𝑛 |
𝑃4

𝑃3

| 

 

�̇�4 −  �̇�3 |1 − 𝑥|. �̇�𝐻𝑃𝑇 

GT Hex 
130 |

𝐴𝐻𝐸𝑋

0.093
|

0.78

 
�̇�5 −  �̇�4 �̇�11 − �̇�12 

GT CC 

|
46.08�̇�5

0.995 −
𝑃7

𝑃5

| |1 + 𝑒𝑥𝑝(0.018𝑇7 − 26.4)| 

�̇�7 �̇�5 + �̇�6 

GT HPT  
|

479.34�̇�7

0.92 − 𝜂𝐻𝑃𝑇

| 𝑙𝑛 |
𝑃7

𝑃8

| |1 + 𝑒𝑥𝑝[0.036𝑇7 − 54.4]| 
�̇�𝐻𝑃𝑇 �̇�7 − �̇�8 

GT REH 

|
46.08�̇�8

0.995 −
𝑃10

𝑃8

| |1 + 𝑒𝑥𝑝(0.018𝑇10 − 26.4)| 

�̇�10 �̇�8 + �̇�9 

GT LPT  
|

479.34�̇�7

0.92 − 𝜂𝐿𝑃𝑇

| 𝑙𝑛 |
𝑃10

𝑃11

| |1 + 𝑒𝑥𝑝[0.036𝑇10 − 54.4]| 
�̇�𝐿𝑃𝑇 �̇�10 − �̇�11 

Kal. Vap Gen. 
130 |

𝐴𝑉𝐴𝑆𝐺𝐸𝑁

0.093
|

0.78

 
�̇�17 − �̇�37 �̇�12 − �̇�13 

Kal. Valve 1 
37 |

𝑃22

𝑃23

|
0.68

 
�̇�23 �̇�22 

Kal. Valve 2 
37 |

𝑃21

𝑃24

|
0.68

 
�̇�24 �̇�21 

Kal. Turb. 
|
479.34�̇�32

0.92 − 𝜂𝑇

| 𝑙𝑛 |
𝑃18

𝑃20

| |1 + 𝑒𝑥𝑝[0.036𝑇18 − 54.4]| 
�̇�𝐿𝑃𝑇 + �̇�𝐾𝑎𝑙𝑃1

+ �̇�𝑉𝐴𝑆𝑃2
 �̇�18 − �̇�20 

Kal. CND 1 
516.62

�̇�𝐾𝑎𝑙𝐶𝑁𝐷1

0.15∆𝑇𝐾𝑎𝑙𝐶𝑁𝐷1

 
�̇�60 − �̇�59 �̇�28 −  �̇�29 

Kal. Valve 3 
37 |

𝑃29

𝑃30

|
0.68

 
�̇�30 �̇�29 

Kal. Evap 1 
309.4 |

�̇�𝐾𝑎𝑙𝐸𝑉𝑃1

0.15∆𝑇𝐾𝑎𝑙𝐸𝑉𝑃1

|

0.85

 
�̇�31 −  �̇�30 �̇�67 − �̇�68 

Kal. HEX 1 
130 |

𝐴𝐾𝑎𝑙𝐻𝐸𝑋1

0.093
|

0.78

 
�̇�37 −  �̇�36 �̇�25 − �̇�26 

Kal. CND 2 
516.62

�̇�𝐾𝑎𝑙𝐶𝑁𝐷2

0.15∆𝑇𝐾𝑎𝑙𝐶𝑁𝐷2

 
�̇�58 −  �̇�57 �̇�33 − �̇�34 

Kal. Pump 1 
705.5 |0.001𝑊̇

𝐾𝑎𝑙𝑃𝑢𝑚𝑝1
|

0.71

|1 +
0.2

1 − 𝜂𝑃

| 
�̇�35 −  �̇�34 �̇�𝐾𝑎𝑙𝑃1

 

VAS HEX 3 
130 |

𝐴𝑉𝐴𝑆𝐻𝐸𝑋3

0.093
|

0.78

 
�̇�44 −  �̇�43 �̇�45 − �̇�46 

VAS Valve 4 
37 |

𝑃39

𝑃40

|
0.68

 
�̇�47 �̇�46 

VAS Pump 2 
705.5 |0.001𝑊̇

𝐾𝑎𝑙𝑃𝑢𝑚𝑝2
|

0.71

|1 +
0.2

1 − 𝜂𝑃

| 
�̇�43 −  �̇�42 �̇�𝑉𝐴𝑆𝑃2

 

VAS EVP 2 
309.4 |

�̇�𝑉𝐴𝑆 𝐸𝑉𝑃2

0.15∆𝑇𝑉𝐴𝑆 𝐸𝑉𝑃2

|

0.85

 
�̇�41 −  �̇�40 �̇�63 − �̇�64 

VAS CND 3 
516.62

�̇�𝑉𝐴𝑆𝐶𝑁𝐷3

0.15∆𝑇𝑉𝐴𝑆𝐶𝑁𝐷3

 
�̇�62 −  �̇�61 �̇�38 −  �̇�39 

Water heater 
130 |

𝐴𝐻𝐸𝐴𝑇𝐸𝑅

0.093
|

0.78

 
�̇�16 −  �̇�15 �̇�13 − �̇�14 

 



FI Abam et al. /Future Technology                                                                                         February 2024| Volume 03 | Issue 01 | Pages 40-55 

46 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The pump has an exergoeconomic factor of 1, suggesting a 
zero contribution to ED costs. This is realistic as the system 
pumps operated in isentropic conditions. The total cost of 
product and fuel for the GT (Table 9) is calculated at 2.67 and 
6.06 $/GJ, respectively, while that for the Kalina (Table 10) 
and VAS subsystems (Table 11) exist at 32.92 and 84.89 $/GJ, 
and 17.97 and 25.93 $/GJ, respectively. The results show a 
lower average energy cost from the GT (0.836 $/GJ) 
compared to the Kalina subsystem and the VAS. For the PEM 
electrolyzer, economic parameters are equally presented in 
Table 12. Furthermore, the exergoeconomic factors (𝑓𝑘) for 
all the subsystems are similarly presented in Tables 9-12, 
estimated at 59.59%, 68 %, 8.656%, 30.71%, 47.41% for GT, 
KAL,  VAS, and PEM electrolyzer respectively. Low values of 
𝑓𝑘 for any system component indicate high ED cost, which 
signifies a high prospective for improvement, while high 
values of relative cost difference (𝑟𝑘) indicate prospects for 
system optimisation. The 𝑟𝑘 for the GT, KAL, VAS, and PEM 
electrolyzer subsystems are calculated at 127 %, 157 %, 30% 
and 30.71 %, respectively. The joined effects of 𝑟𝑘 and 𝑓𝑘 
show that the GT and KAL subsystems have the highest 
potential for improvement, followed by VAS and PEM 
electrolyzer, which have the narrow potential for 
optimisation. 

4.5 Sensitivity analysis  

4.5.1 Effect of dead state temperature on system 
efficiencies 

 Figure 2 presents the effect of dead state temperature 
on system performance. The energy and exergy efficiencies of 
the GT and Kalina cycles and the coefficient of performance of 
the VAS were observed. The dead state temperature (DST) 
ranged between 288 and 302 K.  The results show that the 
DST increase led to a reduction in system efficiency. At high 
DSTs, the compressor work increases, reducing the net 
system output, especially at the topping GT cycle. The results 
also show that for every 5 K rise in DST, the energy and exergy 
efficiency reduced by 0.40 and 0.44 %, respectively. The COP 
of the VAS was estimated at 4.30 and is constant throughout 
the DST range, showing that the DST has no direct link with 
COP measured parameters. 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

4.5.2 Effect of heat input on the PEM electrolyzer heat 
exchanger 

 The effect of the required temperature of heating at 
the inlet to the PEM heat exchanger (HEX) is investigated on 
the hydrogen yield rate (Figure 3). The water inlet from the 
condenser of the Kalina system improves the quantity of the 
hydrogen production rate due to higher PEM water inlet rate 
to cater for the high energy exchange required in the HEX. 
Since the temperature of the water entering the PEM 
electrolyzer is fixed at 95oC, the figure demonstrates the 
range of water temperatures at the PEM HEX. At most, 
102.02OC is required for optimum hydrogen yield with other 
operating PEM electrolyzer parameters constant as indicated 
in its modelling. 

4.5.3 Effect of gasifier temperature on hot water rate 
power output 
Figure 4 shows the effect of gasifier temperature in the 

topping cycle on the quantity of hot water production at a 
given hot water temperature and the magnitude of power in 
the Kalina turbine. Very high gasifier temperatures result in 
slightly reduced biomass syngas calorific value. Thus, the 
energy level of the bottoming cycles, including the water 
heater, is reduced, affecting the quantity of hot water at 95oC. 
However, the power output from the Kalina turbine was 
constant at 181 kW. This is attributable to the fixed operating 
conditions of the Kalina system within a range of heat transfer 
requirements around the Kalina vapour generator. 

4.5.4 Effect of ammonia mass fraction on cooling and 
turbine output 

 The effect of ammonia mass fraction on the power 
output and cooling rate of the Kalina system is presented in 
Figure 5. In the design condition, a mass fraction of 0.28. The 
result indicates that increasing ammonium mass fraction 
leads to a higher turbine work and cooling rate. However, at 
mass fractions higher than 30 per cent, and with the operating 
pressures in the system, the pump work requirements are 
significantly higher than the turbine output. Therefore, it is 
not feasible to operate the system with an ammonia mass 
fraction in excess of 0.30. 

 

 

Table 4. Design operating data [15, 23] 

Parameter Unit 

 

Value 

Ambient temperature o C 25 

Ambient pressure Bar 1.013 

GT Lower compression ratio Dim. 3.162 

GT Higher compression ratio Dim. 3.162 

Overall pressure ratio Dim. 10 

GT Heat exchanger effectiveness % 75 

Low pressure turbine isentropic efficiency % 85 

High pressure turbine isentropic efficiency % 85 

Low pressure compressor isentropic efficiency % 80 

High pressure compressor isentropic efficiency % 80 

mass of air to the topping cycle kg/s 200 

mass of gas at the inlet to the first combustion chamber kg/s 3.131 

mass of gas at the inlet to the reheater kg/s 21.49 

High pressure turbine inlet temperature o K 1350 

Low pressure turbine inlet temperature o K 1200 

The exit temperature of intercooler water o C 85 

  



FI Abam et al. /Future Technology                                                                                         February 2024| Volume 03 | Issue 01 | Pages 40-55 

47 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table 5. Thermodynamic properties at the state points  

State Temperature 
[oC] 

 

Pressure 
[Bar] 

Enthalpy 
[kJ/kg] 

 

Entropy 
[kJ/kg.K] 

 

Mass 
[kg] 

Exergy 
[kW] 

1 25 1.013 298.40 5.695 200 0.00 
2 170.1 3.203 445.00 5.765 200 25150.00 
3 120 3.203 397.90 5.643 200 22965.00 
4 311.3 10.13 590.90 5.72 200 57016.00 
5 523.2 10.13 818.10 6.051 200 82706.00 
6 25 10.13 42300.00 - 2.533 124996.00 
7 977 10.13 1337.00 6.565 202.5 157799.00 
8 689.7 2.843 1004.00 6.628 202.5 86580.00 
9 427 2.843 19841.00 - 2.991 62661.00 

10 927 2.843 1278.00 6.882 205.5 128628.00 
11 696.6 1.013 1012.00 6.932 205.5 70840.00 
12 484.7 1.013 776.00 6.658 205.5 39178.00 
13 471 1.013 761.10 6.638 205.5 37326.00 
14 349.6 1.013 631.20 6.448 205.5 22305 
15 20 1.013 83.30 0.294 85 0.00 
16 95 1.013 397.40 1.248 85 2523.00 
17 180 20 1264.00 3.639 2.5 862.60 
18 180 20 2164.00 5.901 0.97 606.80 
19 - - - - - 4.774 
20 136.9 7 1971.00 5.901 0.97 419.60 
21 136.9 7 509.50 1.753 0.0644 4.69 
22 180 20 694.10 2.205 1.53 206.70 
23 79.8 0.8 694.10 2.39 1.53 122.20 
24 77.6 0.8 509.50 1.821 0.0644 3.39 
25 79.7 0.8 686.70 2.367 1.594 125.60 
26 60 0.8 176.80 0.8905 1.594 14.33 
27 55 0.8 146.50 0.799 1.594 9.42 
28 136.9 7 2080.00 6.209 0.9056 412.80 
29 42.9 7 -42.60 0.48 0.9056 36.90 
30 -5.5 0.8 -42.60 0.5609 0.9056 15.08 
31 15 0.8 332.40 1.909 0.9056 -9.22 
32 43.3 0.8 213.80 1.236 2.5 25.78 
33 38 0.8 123.00 0.9479 2.5 13.61 
34 25 0.8 -73.38 0.3073 2.5 -0.06 
35 25.1 20 -71.24 0.3073 2.5 5.28 
36 40 20 -7.27 0.5168 2.5 9.19 
37 50 20 35.55 0.6514 2.5 15.91 
38 79.7 0.07424 2649.00 8.478 1.5 189.40 
39 41 0.07424 171.10 0.5836 1.5 2.20 
40 1.7 0.006812 171.10 0.6229 1.5 -15.35 
41 1.7 0.006812 2503.00 9.114 1.5 -312.80 
42 34.6 0.006812 92.00 0.1987 11.16 3.02 
43 34.6 0.006812 92.00 0.1987 11.16 3.02 
44 67 0.006812 156.30 0.3978 11.16 58.69 
45 79.7 0.006812 229.30 0.4167 9.661 40.51 
46 45 0.006812 169.30 0.2361 9.661 -19.08 
47 35 0.006812 169.30 0.1817 9.661 137.40 
48 20 1.013 83.30 0.294 37.58 0.00 
49 80 1.013 334.30 1.073 37.58 705.30 
50 20 1.013 83.30 0.294 5 0.00 
51 95 1.013 397.40 1.248 5 148.40 
52 85 1.013 355.30 1.132 10 221.60 
53 85 1.013 4843.00 56.17 0.0000423 0.00 
54 85 1.013 355.30 1.132 5 110.80 
55 85 1.013 55.01 0.1683 0.000336 0.00 
56 85 1.013 355.30 1.132 5 110.80 
57 20 1.013 83.30 0.294 8.383 0.00 
58 34 1.013 141.90 0.4893 8.383 3.18 
59 20 1.013 83.30 0.294 7.065 0.00 
60 85 1.013 355.30 1.132 7.065 156.60 
61 20 1.013 83.30 0.294 44.42 0.00 
62 40 1.013 166.96 0.5702 44.42 59.99 
63 25 1.013 298.42 5.695 151.5 0.00 
64 2 1.013 275.30 5.614 151.5 142.40 
65 20 1.013 83.30 0.294 69.55 0.00 
66 35 1.013 146.00 0.5029 69.55 35.41 
67 25 1.013 298.40 5.695 13.01 0.00 
68 -1 1.013 272.30 5.603 13.01 15.73 
69 33 1.013 137.80 0.4762 15.45 4.14 

 



FI Abam et al. /Future Technology                                                                                         February 2024| Volume 03 | Issue 01 | Pages 40-55 

48 

 

Table 6. Performance parameters of the energy system 

Performance Index Unit Value 
LPC Power MW 29.151 
HPC Power MW 38.743 
LPT Power MW 55.605 
HPT Power MW 68.754 
GT Net Power Output MW 55.605 
GT Relative Exergy Efficiency % 29.63 
Kalina Relative Exergy Efficiency % 11.13 
Kalina Relative Energy Efficiency % 16.97 
VAS COP - 4.304 
Kalina turbine power kW 187.2 
Kalina pump power kW 5.337 
Kalina evaporator cooling kW 339.6 
Kalina Exergy of cooling kW 24.3 
Kalina net power kW 181.9 
VAS evaporator cooling kW 3498 
Exergy of cooling kW 297.4 
VAS desorber heat kW 812.9 
PEM hydrogen output kg/h 0.1524 
System net output MW 86.320 
System net input MW 161.403 
System net energy efficiency % 53.48 
System net exergy efficiency % 50.05 

 

4.5.5 Gasifier mass flow rate on thermo environmental 
parameters and hot water production rate 

 The effect of the gasifier mass flow rate at the reheater 
was investigated on the quantity of hot water production and 
thermo-environmental parameters, as shown in Figure 6. The 
result indicates that the gasifier mass flow rate increases the 
amount of hot water production when maintained at 95 oC. 
This slight increase in gasifier mass flow rate has a negligible 
impact on ETI, decreasing slightly from 2.115 to 2.109 units. 
The trend is attributed to the variation in the flue gas 
temperature after the water heater. Also, similar 
thermodynamic conditions are responsible for a low 
comparative variation on the EUI when the gasifier mass flow 
rate increases. Conversely, increasing the gasifier mass flow 
rate reduces the overall ESI. The system’s ESI dropped from 
0.822 to 0.358, which is attributed to large exergy destruction 
in the reheater and LPT. 

4.5.6 Effect of ammonia mass fraction on thermo-
environmental parameters 
Figure 7 shows the effect of ammonia mass fraction on 

thermo-environmental parameters. The variations in the 
ammonia mass fraction slightly affect the ETI, EUI, and ESI. 
Higher ammonia concentration results in a rich and increased 
quantity of ammonium vapour for expansion in the turbine 
and evaporation in the evaporators. Thus, the power output 
of the Kalina system rises. Nonetheless, since the EUI, ETI, and 
ESI are wholly affected by the variation of the net output from 
the entire multigeneration plant, the effect of Kalina output is 
negligible on these thermo-environmental parameters. 
However, due to high exergy destruction in the Kalina vapour 
generator resulting from the increase in the ammonium 
concentration, the ESI reduces slightly from 0.5279 to 0.5251 
between ammonia concentrations of 0.25 and 0.40. 

4.5.7 Effect of primary zone temperature on 
environmental emissions 
Figure 8 present the effect of the primary zone 

temperature on the production of 𝐶𝑂, CO2 and 𝑁𝑂𝑋 
emissions. The parameters of the primary zone temperature 
in the combustion chamber were estimated using the 
methodology in [24].  

Table 7. Summary of systems component and total exergy 
destruction 

Component Exergy 
destruction 
(ED) 
[kW] 

[%] 
ED/cycle 
and 
component 

[%]  
total of 
ED 

GT CC 49903.00 54.652 46.901 

GT HEX 5971.00 6.539 5.612 

GT HPC 4692.00 5.139 4.409 

GT HPT 2466.00 2.701 2.318 

GT INTCL 1481.00 1.621 1.392 

GT LPC 4001.00 4.382 3.760 

GT LPT 2183.00 2.391 2.052 

GT reheater 20613.00 22.575 19.373 

GT total ED 91310.00 100.000 85.818 

KAL. CND1 219.3.00 15.517 0.206 

KAL. CND2 10.480 0.742 0.009 

KAL. EVP1 8.568 0.606 0.008 

KAL. HEX1 1.813 0.128 0.002 

KAL. HEX2 8.265 0.585 0.008 

KAL. PUMP1 0.003 0.00018 2.5E-06 

KAL. SEP1 49.040 3.469 0.046 

KAL. SEP2 2.147 0.151 0.002 

KAL. TURB 0.000 0.000 0.000 

KAL. VALVE1 84.560 5.983 0.079 

KAL. VALVE2 1.301 0.092 0.001 

KAL. VALVE3 21.820 1.544 0.021 

KAL. VG 1006.00 71.181 0.945 

Kalina total ED 1413.290 100.00 1.328 

VAS absorber 213.900 21.543 0.201 

VAS condenser 2 127.200 12.811 0.119 

VAS desorber 318.800 32.108 0.299 

VAS evaporator 2 155.100 15.621 0.146 

VAS HEX 3 3.942 0.397 0.004 

VAS pump 2 0.000 0.000 0.000 

VAS valve 4 17.550 1.768 0.016 

VAS valve 5 156.400 15.752 0.147 

VAS ED 992.890 100.000 0.933 

Water heater 12502.00 100.000 11.750 

PEM electrolyzer 115.600 63.658 0.109 

PEM HEX 65.990 36.338 0.062 

PEM oxygen 
separator 

0.0060 0.0032 5.5E-06 

 

The primary zone temperature affects the emission rates 
at critical temperatures in excess of 1895 o K. The rate of 𝑁𝑂𝑋 
emissions are higher (10.57 kg at 2400 oK) compared to 𝐶𝑂 
(0.01380 kg at 2400 oK). Consequently, it is recommended to 
operate the system at optimum primary zone temperature to 
reduce  𝑁𝑂𝑋 emissions. The CO2 emissions from the system 
are not directly related to the primary zone temperature but 
to the emissions coefficient of the natural gas after 
combustion and its mass flow rate. However, this system 
calculated the instantaneous CO2 emissions at 27.35 kg/s at a 
flue gas mass flow rate of 205.5 kg/s. 



FI Abam et al. /Future Technology                                                                                         February 2024| Volume 03 | Issue 01 | Pages 40-55 

49 

 

Table 8. Summary of initial investment, monetary flow rate 
and Levelized capital cost rate 

 
Plant component 

 
Purchase 
of 
equipment 
cost ($) * 

 
Levelized 
cost per 
year 
($/yr.)* 

Levelized 
cost per 
hour 
($/hr.) * 

GT CC 213978 38022 5.038 

GT HEX 155098 27559 3.652 

GT HPC 517708 91992 12.19 

GT HPT 1762604 313198 41.5 

GT INTCL 93214 16563 2.195 

GT LPC 517708 91992 12.19 

GT LPT 1452180 258038 34.19 

GT reheater 213093 37864 5.017 

KAL. CND1 1953 347 0.04598 

KAL. CND2 1953 347 0.04598 

KAL. EVP1 1953 347 0.04598 

KAL. HEX1 3353 595.9 0.07895 

KAL. HEX2 3353 595.9 0.07895 

KAL. PUMP1 5405 960.5 0.1273 

KAL. SEP1 13067 2322 0.3076 

KAL. SEP2 13067 2322 0.3076 

KAL. TURB 156801 27862 3.692 

KAL. VALVE1 325.5 57.83 0.007663 

KAL. VALVE2 325.5 57.83 0.007663 

KAL. VALVE3 325.5 57.83 0.007663 

KAL. VG 191786 34079 4.515 

VAS absorber 1060 188.3 0.02495 

VAS condenser 3 1137 202.1 0.02678 

VAS desorber 2679 476.1 0.06308 

VAS evaporator 2 1017 180.7 0.02395 

VAS HEX 3 1254 222.8 0.02952 

VAS pump 2 5321 940.3 0.0123 

VAS valve 4 325.5 57.83 0.007663 

VAS valve 5 325.5 57.83 0.007663 

Water heater 2444 434.3 0.05755 

PEM electrolyser 3823 679.2 0.0225 

PEM HEX 955.6 169.8 0.0225 

PEM oxygen separator 1147 203.8 0.027 

 

4.5.8 Effect of gasifier temperature and mass flow on the 
unit cost of electricity  

 The effect of gasifier temperature and mass flow rate 
on the unit cost of electricity is shown in Figure 9. The 
temperature of the gasifier and the mass flow correlate with 
the unit cost of electricity (UCOE) regarding the system power 
output. The UCOE based on the initial design conditions was 
obtained as 21.44 N/kWh (USD 0.0329/kWh), which is more 
attractive than the current tariff plan in Nigeria of 54 N/kWh 
(USD 0.083/kWh). The gasifier temperature and the mass 
flow rate increase leads to a decrease in the UCOE following a 
high output generation from the system. Therefore, the 
reduction in UCOE is more with respect to the gasifier 
temperature increase than the gasifier mass flow rate. 

4.5.9 Effect of ammonium mass fraction on the unit cost 
of electricity  

 The effect of ammonia mass fraction on the UCOE and 
PEC for the entire system is shown in Figure 10. The increase 
in ammonia mass fraction leads to a slight increase in the 

UCOE. High ammonium mass fraction results in high turbine 
output, which increases the turbine purchase equipment cost.  
Although there is an additional power generation from a high 
ammonium mass fraction, the UCOE increase is negligible.  

 
Figure 2. Dead state temperature on performance 
parameters 

 
Figure 3. Effect of heat input on the PEM electrolyzer heat 
exchanger 
 
 

 
Figure 4. Gasifier temperature effect on hot water production 
rate and power output 

 

 

288 290 292 294 296 298 300 302
49

50

51

52

53

54

55

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

Dead state temperature (K)

E
n

er
g
y
 a

n
d

 e
x
er

g
y
 e

ff
ic

ie
n

cy
 (

%
)

Exergy efficiencyExergy efficiencyEnergy efficiencyEnergy efficiency

V
A

S
 C

O
P

VAS COPVAS COP

500 600 700 800 900

24

26

28

30

32

34

36

100

120

140

160

180

200

Gasifier temperature (
o
C)

H
o
t 

w
a
te

r
 p

r
o
d

u
c
ti

o
n

 r
a
te

 (
k

g
/s

)

Hot waterHot water

K
a
li

n
a
 t

u
r
b

in
e
 o

u
tp

u
t 

(k
W

)

Kalina turbine outputKalina turbine output



FI Abam et al. /Future Technology                                                                                         February 2024| Volume 03 | Issue 01 | Pages 40-55 

50 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 
 

4.5.10 Effect of gasifier temperature and mass flow on 
system total cost  

 In Figure 11, the effect of gasifier mass flow rate and 
temperature is investigated on the system's total cost. The 
system’s net cost was estimated at $ 5335411.5 based on the 
operating conditions in Table 6. The total cost comprises 
purchasing equipment (PEC) for all system components. Thus 
an increase in both the gasifier temperature and mass flow 
rate significantly raises the total PEC of the system.  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 
 

The resultant effect of increased gasifier temperature and 
mass flow rate cumulatively enhances the power 
requirements of the LPT. Consequently, the PEC of the LPT, 
GT HEX, Kalina vapour generator, and water heater 
contributes about 33.76 % of the entire plant's PEC. 

4.6 Optimum parameters 

For optimal performance, the study considered the 

following objective functions (OBF): total exergy efficiency 

Table 9. Exergoeconomic parameters for the GT and reheater topping cycle 

Component �̇�𝑭 

($/GJ) 

�̇�𝑷 

($/GJ) 

�̇�𝑫 

(MW) 

�̇�𝑫 

($/hr.) 

𝒁 

($/hr.) 

𝒁 + �̇�𝑫 

($/hr.) 

𝒇𝒌 

(%) 

𝒓𝒌 

(%) 
GT CC 0.2217 0.3007 49.903 39.8243 5.038 44.8623 11.30 35.63 

GT HEX 0.2139 0.3028 5.971 4.597719 3.652 8.2497 44.30 41.55 

GT HPC 0.3649 0.6516 4.692 6.165175 12.19 18.355 66.40 78.53 

GT HPT 0.3007 0.4851 2.466 2.669287 41.5 44.169 93.40 61.34 

GT INTC 0.6967 3.0239 1.481 3.714362 2.195 5.909 37.10 334.06 

GT LPC 0.4851 0.6969 4.001 6.986962 12.19 19.177 63.50 43.67 

GT LPT 0.2139 0.3930 2.183 1.680655 34.19 35.871 95.30 83.77 

GT REH 0.1749 0.2139 20.613 12.98443 5.017 18.001 27.90 22.22 
 

Table 10. Exergoeconomic parameters for the Kalina power-cooling bottoming cycle 

Component �̇�𝑭 

($/GJ) 

�̇�𝑷 

($/GJ) 

�̇�𝑫 

(MW) 

�̇�𝑫 

($/hr.) 

𝒁 

($/hr.) 

𝒁 + �̇�𝑫 

($/hr.) 

𝒇𝒌 

(%) 

𝒓𝒌 

(%) 
KAL. CND1 2.5492 6.1994 0.2193 2.0126 0.0460 2.0585 2.230 143.190 
KAL. CND2 2.4799 14.579 0.0105 0.0935 0.0459 0.1395 32.95 487.876 
KAL. EVP1 1.0000 2.1805 0.0086 0.0000 0.0459 0.0459 100.00 118.051 
KAL. HEX1 1.9857 4.7164 0.0018 0.0130 0.0789 0.0919 85.89 137.515 
KAL. HEX2 2.4787 13.327 0.0083 0.0738 0.0789 0.1527 51.70 437.671 
KAL. PUM1 8.0153 14.968 2.6E-06 7.5E-05 0.1273 0.1274 99.94 86.738 
KAL. SEP1 2.1012 2.3329 0.0490 0.3710 0.3076 0.6786 45.33 11.025 
KAL. SEP2 2.3329 2.5496 0.0022 0.0180 0.3076 0.3256 94.46 9.2890 
KAL. TURB 2.3326 7.5825 0.0000 0.0000 3.6920 3.6920 100.00 225.064 
KAL. VAL1 2.3329 3.9644 0.0846 0.7102 0.0077 0.7179 1.07 69.928 
KAL. VAL2 2.5474 4.1527 0.0013 0.0119 0.0077 0.0196 3.91 63.019 
KAL. VAL3 2.5542 6.3918 0.0218 0.2006 0.0077 0.2083 3.68 150.247 
KAL. VG 0.2129 1.9493 1.0060 0.7713 4.5150 5.2864 85.41 815.217 

 

Table 11. Exergoeconomic parameters for the vapor absorption bottoming cycle 

Component �̇�𝑭 
($/GJ) 

�̇�𝑷 
($/GJ) 

�̇�𝑫 
(MW) 

�̇�𝑫 
($/hr.) 

𝒁 
($/hr.) 

𝒁 + �̇�𝑫 
($/hr.) 

𝒇𝒌 
(%) 

𝒓𝒌 
(%) 

VAS ABS 0.0909 1.2461 0.2139 0.0701 0.0250 0.0950 26.26 1269.62 
VAS CON 3 1.4121 4.5304 0.1272 0.6466 0.0268 0.6734 3.980 220.82 
VAS DESB 0.8303 1.4123 0.3188 0.9529 0.0631 1.0160 6.210 70.097 
VAS evaporator 2 1.0001 1.0224 0.1551 0.0000 0.0240 0.0240 100.00 2.23 
VAS HEX 3 0.3313 0.6916 0.0039 0.0047 0.0296 0.0342 86.26 108.76 
VAS pump 2 15.014 17.473 0.0000 0.0000 1.02E-07 1.02E-07 100.00 16.38 
VAS valve 4 0.1408 0.3406 0.0176 0.0089 0.0077 0.01660 46.28 141.91 
VAS valve 5 20.663 24.9180 0.0031 0.2290 0.0050 0.2340 97.69 20.59 

 

Table 12. Exergoeconomic parameters for the PEM electrolyzer 

Component �̇�𝑭 
($/GJ) 

�̇�𝑷 
($/GJ) 

�̇�𝑫 
(MW) 

�̇�𝑫 
($/hr.) 

𝒁 
($/hr.) 

𝒁 + �̇�𝑫 
($/hr.) 

𝒇𝒌 
(%) 

𝒓𝒌 
(%) 

WATER heater 0.2140 1.2793 12.502 9.6297 0.05755 9.6873 5.9 497.93 
PEM Electrolyzer 4.5650 9.3813 0.116 1.8998 0.0225 1.9223 1.17 105.50 
PEM HEX 6.3660 6.7198 0.066 1.5124 0.0225 1.5348 1.47 5.56 
PEM oxygen separator 9.3813 9.4491 5.79E-06 0.0002 0.0270 0.027196 99.28 0.723 

 

 
 

 



FI Abam et al. /Future Technology                                                                                         February 2024| Volume 03 | Issue 01 | Pages 40-55 

51 

 

(𝜓) and the total product cost rate. The 𝜓 is to be maximized, 

while the total cost rate is to be reduced or maximized.  The 

total cost rate model equation of the multigeneration plant is 

integrated with the cost rate of the pollution damage.   

 

Figure 5. Effect of ammonia mass fraction on Kalina cycle 

performance 

 

 

Figure 6. Gasifier mass flow rate on environmental 

parameters and hot water production rate 

 

Figure 7. Effect of ammonia mass fraction on thermo 

environmental parameter 

The OBFs are described as follows:  

𝜓𝑜𝑣𝑒𝑟𝑎𝑙𝑙 =

{�̇�𝑊𝐿𝑃𝑇
+�̇�𝑊𝐻𝑃𝑇

+�̇�𝑊𝐾𝑇
+�̇�𝑅𝐾𝑎𝑙𝑖𝑛𝑎

+�̇�𝑅𝑉𝐴𝑆
}−{�̇�𝑊𝐿𝑃𝐶

+�̇�𝑊𝐻𝑃𝐶
+∑ �̇�𝑊𝑃𝑖

6
𝑖=1 }

𝐴𝑑
  

                           (26) 

Where 𝐴𝑑  of Eq (26) is expressed in Eq (27).  

𝐴𝑑 = ‖[1 −
𝑇0

𝑇6
] �̇�6 + [1 −

𝑇0

𝑇9
] �̇�9‖                          (27)

       

Where �̇�6 and �̇�9 are the heat addition into the GT combustion 
chamber and the complementary firing process (the 
reheater) Figure 1.  

 
Figure 8. Effect of primary zone temperature on 
environmental emissions 

 

Figure 9. Effect of gasifier temperature and mass flow on the 
unit cost of electricity 

 

Figure 10. Effect of ammonia mass fraction on the unit cost of 
electricity 

 

1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
24.0

24.1

24.2

24.3

24.4

24.5

0.0

0.5

1.0

1.5

2.0

2.5

Gasifier mass flow rate (kg/s)

H
ot

 w
at

er
 p

ro
d

u
ct

io
n

 r
at

e 
(l

it
re

s)

Hot waterHot water

T
h

er
m

oe
n

vi
ro

n
m

en
ta

l 
p

ar
am

et
er

s

ESIESIETIETI EUIEUI

1500 2000 2500

0

5000

10000

15000

20000

25000

30000

Primary zone temperature (
o
K)

E
m

is
si

on
s 

(g
ra

m
s)

NOxNOx COCO CO2CO2

500 600 700 800 900 1000
20

22

24

26

28

30

32

34
1.5 2 2.5 3 3.5 4 4.5 5

21.3

21.4

21.5

21.6

Gasifier temperature (
o
C)

U
C

O
E

 (
N

/k
W

h
) 

at
 d

if
f.

 g
as

if
ie

r 
te

m
p

.

UCOE at diff. gasifier temp.UCOE at diff. gasifier temp.

Gasifier mass flow rate (kg/s)

U
C

O
E

 (
N

/k
W

h
) 

at
 d

if
f.

 g
as

if
ie

r 
m

as
s 

fl
ow

UCOE at diff. gasifier mass flowUCOE at diff. gasifier mass flow

0.25 0.3 0.35 0.4
21.0

21.5

22.0

22.5

23.0

120000

140000

160000

180000

200000

220000

240000

Ammonia mass fraction in water

U
C

O
E

 (
N

/k
W

h
)

UCOEUCOE
K

a
li

n
a
 T

u
rb

in
e 

P
E

C
 (

$
)

Kalina Turbine PECKalina Turbine PEC

0.250 0.300 0.350 0.400

0.50

1.00

1.50

2.00

Ammonia mass fraction in water

T
h

er
m

o
-e

n
v
ir

o
n

m
en

ta
l 

p
a
ra

m
et

er
s

ESIESI

ETIETI

EUIEUI

0.25 0.3 0.35 0.4

150

200

250

300

200

300

400

500

600

Ammonia mass fraction in water

K
a
li

n
a
 t

u
rb

in
e 

o
u

tp
u

t 
(k

W
)

Kal turb. outputKal turb. output

K
a
li

n
a
 e

v
a
p

o
ra

to
r 

co
o
li

n
g
 r

a
te

 (
k

W
)

Kalina evap. coolingKalina evap. cooling



FI Abam et al. /Future Technology                                                                                         February 2024| Volume 03 | Issue 01 | Pages 40-55 

52 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The total cost rate of the system and the cost rate due to 
environmental impact are presented in Eqs (28) and (29). The 
components of the optimization function, objective functions, 
constraints and key performance indices are depicted in 
Table 13. 

�̇�𝑇𝑜𝑡 = �̇�𝑓𝑢𝑒𝑙 + �̇�𝑒𝑛𝑣. + ∑ �̇�𝑘𝑘         (28) 

�̇�𝑒𝑛𝑣 = 𝐶𝑁𝑂𝑥
�̇�𝑁𝑂𝑥

+ 𝐶𝐶𝑂2
�̇�𝐶𝑂2

+ 𝐶𝐶𝑂�̇�𝐶𝑂       (29) 

Where the unit damage costs 𝐶𝑁𝑂𝑥
, 𝐶𝐶𝑂2

 and 𝐶𝐶𝑂 are taken as 

0.02186 $/kg, 6.863$/kg and 0.023 $/kg, respectively.  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The GA (genetic algorithm) was applied in the optimization 
due to its flexibility in simplifying multi-variable and multi-
objective problems. In this analysis, Ninety groups of the 
Pareto-frontiers from the GA were described following the 
OBFs and the equivalent constraints. The 17th Pareto-front 
correspond to the optimum (𝜓) and minimum cost rate 
calculated at 45.32 % and 125.84 $/hr, separately. The 
corresponding parameters occur at a compression ratio (CR) 
of 8, with isentropic efficiencies of LPC, HPC, LPT, and HPT 
existing at 88%. Also, the intercooler exit temperature and the 
inlet temperature to the combustion chamber and reheater 
were calculated at 386.7K, 1140 K and 1240.3 K. The optimal 

500 600 700 800 900 1000
5.100x10

6

5.150x10
6

5.200x10
6

5.250x10
6

5.300x10
6

5.350x10
6

1.5 2 2.5 3 3.5 4 4.5 5

5.320x10
6

5.325x10
6

5.330x10
6

5.335x10
6

5.340x10
6

5.345x10
6

5.350x10
6

5.355x10
6

Gasifier temperature (
o
C)

Sy
st

em
 to

ta
l c

os
t (

$)
 (

fr
om

 b
io

m
as

s 
ga

s.
 te

m
p.

Total cost at varying gasifier temp.Total cost at varying gasifier temp.

Gasifier mass flow rate (kg/s)

Sy
st

em
 to

ta
l c

os
t (

$)
 (

fr
om

 b
io

m
as

s 
m

as
s 

va
ri

at
io

n)

Total cost at varying gasifier mass flowTotal cost at varying gasifier mass flow

Table 13. Components of optimization functions and parameters 

Performance 

index 

Optimization function Decision variables Optimization constraints 

𝐖𝐋𝐏𝐂 �̇�1𝑐𝑝

𝑇1

𝜂𝐿𝑃𝐶

[(𝑟𝑝)
𝑘

− 1] 𝜂𝐿𝑃𝐶 ,   𝑟𝑝   

 

0.80 ≤ 𝐿𝑃𝐶 ≤ 0.90 

𝐖𝐇𝐏𝐂 �̇�3𝑐𝑝

𝑇3

𝜂𝐻𝑃𝐶

[(𝑟𝑝)
𝑘

− 1] 𝜂𝐿𝑃𝐶 ,   𝑟𝑝   

 

0.80 ≤ 𝐿𝑃𝐶 ≤ 0.90 

𝐖𝐋𝐏𝐓 
�̇�10𝑐𝑝𝑇10𝜂𝐿𝑃𝑇 |1 −

1

(𝑟𝑝)
𝑘| 

𝜂𝐿𝑃𝐶 ,   𝑟𝑝,   𝑇10 

   

 

0.80 ≤ 𝐿𝑃𝐶 ≤ 0.9 

 8≤ 𝑟𝑝 ≤ 16,1150 ≤ 𝑇10 ≤ 1250 

𝐖𝐇𝐏𝐓 
�̇�7𝑐𝑝𝑇7𝜂𝐻𝑃𝑇 |1 −

1

(𝑟𝑝)
𝑘| 

𝜂𝐿𝑃𝐶 ,   𝑟𝑝,   𝑇7 

 

0.80 ≤ 𝐿𝑃𝐶 ≤ 0.9, 8 ≤ 𝑟𝑝 ≤

16, 1150 ≤ 𝑇7 ≤ 1250 𝐾 

𝐖𝐊𝐚𝐥.𝐓𝐮𝐫𝐛 �̇�28|ℎ28 − ℎ29| + 

|�̇�28 − �̇�29|. |ℎ29 − ℎ33| 

𝑃28, pressure at 𝑇28, ℎ28 

 

435 ≤ 𝑇28 ≤ 439 K 

𝐐𝐄𝐕𝐏𝟏 �̇�30|ℎ31 − ℎ32| 𝑇30 

 

𝑇61, -3 and -1.5 OC 

𝐕𝐏𝐠𝐞𝐧𝐞𝐫𝐚𝐭𝐨𝐫 �̇�12|ℎ12 − ℎ13| 𝑇12 

 

270 ≤ 𝑇60 ≤ 282 

𝐐𝐄𝐕𝐏𝟐 �̇�40|ℎ41 − ℎ40| 𝑇40 

 

𝑇44, -5.8 and -1.5 OC 

�̇�𝐨𝐬𝐭,𝐓𝐨𝐭𝐚𝐥 �̇�𝑓𝑢𝑒𝑙 + �̇�𝑒𝑛𝑣. + ∑ �̇�𝑘

𝑘

  Described parameters  

 

Figure 11. Effect of gasifier temperature and mass flow on system total cost 



FI Abam et al. /Future Technology                                                                                         February 2024| Volume 03 | Issue 01 | Pages 40-55 

53 

 

inlet pressures of the Kalina system were obtained at 20 kPa. 
The specific emissions rate at the optimum operating 
conditions are calculated at 123.34, 2.87E-07 and 0.214 kg/
MWh for CO2, CO and NOx, respectively. The improvement 
potential of the environmental discharges is for CO2, 1.56 %, 
NOx, 4.33 % and CO, 3.65 %, with optimum hydrogen 
production. 

5. Conclusion 

A Kalina-based multigeneration cycle with increased 
heat addition to the PEM electrolyzer for hydrogen and water 
production was performed. The results are summarised as 
follows: The multigeneration energy system has a net energy 
and exergy efficiency of 53.48 and 50.05 %, respectively. 
Additionally, the system has improved topping cycle 
efficiency by 19.03 and 2.58 %, respectively, from the original 
values of 34.45 and 47.47 %. At the cycle level, the gas turbine 
contributed up to 85.81 % of the ED. The combustion 
chamber and reheater contributed about 54.65 and 22.57 % 
of the total ED destructions. The system overall exergo-
thermal index (ETI) stood at 1.713 with the gas turbine 
system alone the ETI was obtained as 2.106, which suggests a 
higher thermal impact on the environment without the 
addition of the lower cycles. The system has a hydrogen 
production rate of 0.1524 kg/h with cooling rate and COP 
calculated at 3498 kW and 4.304 respectively. The ESI for the 
system was relatively low, with a value of 0.5242. The low ESI 
arises from the large ED in the topping cycle, which 
contributed about 66 % of total system ED. The 
exergoeconomic result indicates a low average cost of energy 
from the gas turbine (0.836 $/GJ) compared to the Kalina 
subsystem (6.53 $/GJ) and vapour absorption system (3.24 
$/GJ).  

Ethical issue 
The authors are aware of and comply with best practices in 
publication ethics, specifically with regard to authorship 
(avoidance of guest authorship), dual submission, 
manipulation of figures, competing interests, and compliance 
with policies on research ethics. The author adheres to 
publication requirements that the submitted work is original 
and has not been published elsewhere. 

Data availability statement 
Datasets analyzed during the current study are available and 

can be given following a reasonable request from the 

corresponding author. 

Conflict of interest 

The authors declare no potential conflict of interest. 

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(https://creativecommons.org/licenses/by/4.0/). 



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Appendix 

                   Table 1. Summary of the energy and exergy balances, as well as the exergy of fuel and product for the system 

Component Energy Balance Exergy Balance Exergy of Fuel Exergy of Product 
GT LPC �̇�1ℎ1 + �̇�𝐿𝑃𝐶  =  �̇�2ℎ2 �̇�1 + �̇�𝐿𝑃𝐶 =  �̇�2 + �̇�𝐷,𝐿𝑃𝐶  �̇�𝐿𝑃𝐶  �̇�2 − �̇�1 
GT intercooler �̇�2ℎ2 + �̇�48ℎ48 =  �̇�3ℎ3 + �̇�49ℎ49 �̇�2 + �̇�48 =  �̇�3 + �̇�49 + �̇�𝐷,   𝐼𝑁𝑇  �̇�2 − �̇�3 �̇�49 − �̇�48 
GT HPC �̇�3ℎ3 + �̇�𝐻𝑃𝐶  =  �̇�4ℎ4 �̇�3 + �̇�𝐿𝑃𝐶 =  �̇�4 + �̇�𝐷,𝐻𝑃𝐶  �̇�𝐻𝑃𝐶  �̇�4 − �̇�3 
GT Hex �̇�4ℎ4 + �̇�11ℎ11 =  �̇�5ℎ5 + �̇�12ℎ12 �̇�4 + �̇�11 =  �̇�5 + �̇�12 + �̇�𝐷,𝐺𝑇 𝐻𝐸𝑋  �̇�11 − �̇�12 �̇�5 − �̇�4 
GT CC �̇�6|𝐿𝐻𝑉6| +  �̇�5ℎ5 =  �̇�7ℎ7 �̇�5 + �̇�6 =  �̇�7 +  �̇�𝐷,𝐺𝑇 𝐶𝐶  �̇�5 + �̇�6 �̇�7 
GT HPT  �̇�7ℎ7  =  �̇�8ℎ8 + �̇�𝐻𝑃𝑇 �̇�7  =  �̇�8 + �̇�𝐻𝑃𝐶 + �̇�𝐿𝑃𝐶 +�̇�𝐷,𝐻𝑃𝑇  �̇�7 − �̇�8 �̇�𝐻𝑃𝐶 + �̇�𝐿𝑃𝐶 
GT REH �̇�9|𝐿𝐻𝑉9| + �̇�8ℎ8 =  �̇�10ℎ10 �̇�8 + �̇�9 =  �̇�10 + �̇�𝐷,𝐺𝑇 𝑅𝐸𝐻  �̇�8 + �̇�9 �̇�10 
GT LPT  �̇�10ℎ10  =  �̇�11ℎ11 + �̇�𝐿𝑃𝑇 �̇�10  =  �̇�11 + �̇�𝐿𝑃𝑇 + �̇�𝐷,𝐿𝑃𝑇  �̇�10 − �̇�11 �̇�𝐿𝑃𝑇  
Kal. Vap Gen. �̇�12ℎ12 +  �̇�37ℎ37 =  �̇�13ℎ13 + �̇�17ℎ17 �̇�12 + �̇�37 =  �̇�13 + �̇�17 + �̇�𝐷,𝑉𝑎𝑝𝐺𝑒𝑛  �̇�12 − �̇�13 �̇�17 − �̇�37 

Kal. Sep 1 �̇�17ℎ17 =  �̇�18ℎ18 +  �̇�22ℎ22 �̇�17 =  �̇�18 + �̇�22 +  �̇�𝐷,𝐾𝑎𝑙 𝑆1  �̇�17 �̇�18 + �̇�22 
Kal. Valve 1 �̇�22ℎ22 =  �̇�23ℎ23 �̇�22 =  �̇�23 + �̇�𝐷,𝐾𝑎𝑙 𝑉1  �̇�22 �̇�23 
Kal. Valve 2 �̇�21ℎ21 =  �̇�24ℎ24 �̇�21 =  �̇�24 + �̇�𝐷,𝐾𝑎𝑙 𝑉2  �̇�21 �̇�24 
Kal. Turb. �̇�18ℎ18 =  �̇�20ℎ20 + �̇�18𝑊𝑇𝐾𝑎𝑙

+ �̇�34𝑊𝑃1
+ �̇�42𝑊𝑃2

 �̇�18 = �̇�20 + �̇�𝑊𝑇𝐾𝑎𝑙
+ �̇�𝑊𝑃1

+ �̇�𝑊𝑃2
+ �̇�𝐷𝑇𝐾𝑎𝑙

 �̇�18 − �̇�20 �̇�𝑊𝑇𝐾𝑎𝑙
+ �̇�𝑊𝑃1

+ �̇�𝑊𝑃2
 

Kal. Sep 2 �̇�20ℎ20 =  �̇�28ℎ28 +  �̇�21ℎ21 �̇�20 =  �̇�28 + �̇�21 +  �̇�𝐷,𝐾𝑎𝑙 𝑆2  �̇�20 �̇�28 + �̇�21 

Kal. CND 1 �̇�28ℎ28 +  �̇�59ℎ59 =  �̇�29ℎ29 + �̇�60ℎ60 �̇�28 + �̇�59 =  �̇�29 + �̇�60 + �̇�𝐷,𝐶𝑁𝐷1  �̇�28 − �̇�29 �̇�60 − �̇�59 
Kal. Valve 3 �̇�28ℎ28 =  �̇�29ℎ29 �̇�28 =  �̇�29 + �̇�𝐷,𝐾𝑎𝑙 𝑉3  �̇�28 �̇�29 
Kal. Evap 1 �̇�12ℎ12 +  �̇�37ℎ37 =  �̇�13ℎ13 + �̇�17ℎ17 �̇�12 + �̇�37 =  �̇�13 + �̇�17 + �̇�𝐷,𝑉.𝐺𝐸𝑁  �̇�12 − �̇�13 �̇�17 − �̇�37 
Kal. HEX 1 �̇�26ℎ26 +  �̇�36ℎ36 =  �̇�27ℎ27 + �̇�37ℎ37 �̇�26 + �̇�36 =  �̇�27 + �̇�37 + �̇�𝐷,𝐾𝑎𝑙 𝐻𝑋𝐸1  �̇�26 − �̇�27 �̇�37 − �̇�36 
Kal. HEX 2 �̇�32ℎ32 +  �̇�35ℎ35 =  �̇�33ℎ33 + �̇�36ℎ36 �̇�32 + �̇�35 =  �̇�33 + �̇�36 + �̇�𝐷,𝐾𝑎𝑙 𝐻𝐸𝑋2  �̇�32 − �̇�33 �̇�36 − �̇�35 
Kal. CND 2 �̇�33ℎ33 +  �̇�57ℎ57 =  �̇�34ℎ34 + �̇�58ℎ58 �̇�33 + �̇�57 =  �̇�34 + �̇�58 + �̇�𝐷,𝐾𝐴𝐿 𝐶𝑁𝐷2  �̇�33 − �̇�34 �̇�58 − �̇�57 
Kal. Pump 1 �̇�34ℎ34 + �̇�34𝑊𝑃1

= �̇�35ℎ35 �̇�34 + �̇�𝑊𝑃1
=  �̇�35 + �̇�𝐷,𝑃1  �̇�𝑊𝑃1

 �̇�35 − �̇�34 

VAS desorber �̇�25ℎ25 +  �̇�44ℎ44 =  �̇�26ℎ26 + �̇�38ℎ38 + �̇�45ℎ45 �̇�25 + �̇�44 =  �̇�26 + �̇�38 + �̇�45 +  �̇�𝐷,𝐷𝐸𝑆𝐵  �̇�25 − �̇�26 + �̇�44 �̇�38 − �̇�45 
VAS HEX 3 �̇�43ℎ43 +  �̇�45ℎ45 =  �̇�44ℎ44 + �̇�46ℎ46 �̇�43 + �̇�45 =  �̇�44 + �̇�46 + �̇�𝐷,𝑉𝐴𝑆 𝐻𝐸𝑋3  �̇�45 − �̇�46 �̇�44 − �̇�43 
VAS Valve 5 �̇�46ℎ46 =  �̇�47ℎ47 �̇�46 =  �̇�47 + �̇�𝐷,𝑉𝐴𝑆 𝑉5  �̇�46 �̇�47 
VAS Pump 2 �̇�42ℎ42 + �̇�42𝑊𝑃2

= �̇�43ℎ43 �̇�42 + �̇�𝑊𝑃2
=  �̇�43 + �̇�𝐷,𝑃2  �̇�𝑊𝑃2

 �̇�43 − �̇�42 

VAS Absorber �̇�41ℎ41 +  �̇�47ℎ47 + �̇�65ℎ65 =  �̇�42ℎ42 + �̇�66ℎ66 �̇�41 + �̇�47 + �̇�65 =  �̇�42 + �̇�66 +  �̇�𝐷,𝐴𝐵𝑆𝐵  �̇�41 + �̇�47 �̇�66 − �̇�65 + �̇�42 
VAS EVP 2 �̇�40ℎ40 +  �̇�63ℎ63 =  �̇�41ℎ41 + �̇�64ℎ64 �̇�40 + �̇�63 =  �̇�41 + �̇�64 + �̇�𝐷,𝑉𝐴𝑆 𝐸𝑉𝑃2  �̇�63 − �̇�64 �̇�41 − �̇�40 
VAS Valve 4 �̇�39ℎ39 =  �̇�40ℎ40 �̇�39 =  �̇�40 + �̇�𝐷,𝑉𝐴𝑆 𝑉4  �̇�39 �̇�40 
VAS CND 3 �̇�38ℎ38 +  �̇�61ℎ61 =  �̇�39ℎ39 +  �̇�62ℎ62 �̇�38 + �̇�61 =  �̇�39 + �̇�62 + �̇�𝐷,𝑉𝐴𝑆 𝐶𝑁𝐷3  �̇�38 − �̇�39 �̇�62 − �̇�61 
Water heater �̇�13ℎ13 +  �̇�15ℎ15 =  �̇�14ℎ14 + �̇�16ℎ16 �̇�13 + �̇�15 =  �̇�14 + �̇�16 + �̇�𝐷,𝐻𝐸𝐴𝑇𝐸𝑅  �̇�13 − �̇�14 �̇�16 − �̇�15 
PEM Electr. �̇�52ℎ52 +  �̇�19ℎ19 =  �̇�53ℎ53 +  �̇�54ℎ54 �̇�52 + �̇�19 =  �̇�53 +  �̇�54 +  �̇�𝐷,𝐸𝑙𝑒𝑐𝑡𝑟𝑜𝑙𝑦𝑠𝑒𝑟  �̇�52 + �̇�19 �̇�53 + �̇�54 

PEM HEX �̇�58ℎ58 +  �̇�60ℎ60 + �̇�50ℎ50 =  �̇�51ℎ51 + �̇�69ℎ69 �̇�58 + �̇�60 + �̇�50 =  �̇�51 +  �̇�69 + �̇�𝐷,𝑃𝐸𝑀 𝐻𝐸𝑋  �̇�58 + �̇�60 − �̇�69 �̇�51 − �̇�50 
PEM O2 
separator 

�̇�54ℎ54 =  �̇�55ℎ55 +  �̇�56ℎ56 �̇�54 =  �̇�55 + �̇�56 +  �̇�𝐷,𝑂𝑥𝑦.𝑠𝑒𝑝  �̇�54 �̇�55 + �̇�56 

 

FI         
             Abam et al. /Future Technology                                                                                                      February 2024| Volume 03 | Issue 01 | Pages 40-55 

 


