Highest Exergy Loss Research Articles

Optimisation of Brayton cycle CO2-based binary mixtures: An application for waste heat recovery of marine low-speed diesel engines exhaust gas

The energy-saving capabilities and efficient operation of marine low-speed diesel engines (MLDE) is a key emphasis for the main power source for ocean transportation. The purpose of the supercritical carbon dioxide recompression Brayton cycle (SCRBC) is to capture and utilise waste heat emitted by the engine's exhaust gas. However, the SCRBC performance will be severely affected by the large temperature fluctuations of ocean-going vessels during operation and high ambient temperatures in the cabin. A SCRBC model was built using the exhaust gas test data as the boundary conditions and validated using the Sandia National Laboratory (SNL) test data. The physical characteristics of the working fluids were evaluated by adding other fluids to CO2 in specific proportions to modify the critical point and increase cycle efficiency. The results demonstrated that employing CO2-based binary working fluids with low alkane and hydrogen sulfide (H2S) enhanced the recovery power, with the most significant increase obtained by the addition of 16.48 % H2S, which increased the power by 9.72 kW and improved the Brayton cycle efficiency by 3.31 %. Compared to the MLDE at 100 % load, the total efficiency increased by 1.77 % and the BSFC decreased by 6.76 (g kW−1 h−1) using CO2-H2S as the working fluid. The analysis of the SCRBC system component exergy losses showed that the cooler had the highest exergy losses. Adding other fluids to CO2 reduced the exergy losses of each component with the SCRBC system exergy losses decreasing from 162.97 to 129.90 kW and the exergy loss efficiency decreasing from 24.24 % to 22.65 %. The use of CO2-based binary working fluids specifically designed for ambient temperature may be expanded to other engines to enhance the efficiency of waste heat recovery.

The evaluation of hydrogen production of a multistage cooling system's performance

In the present research, a new cycle of scramjet open recuperator cooling to produce power and hydrogen is presented. In which, the power generation subsection uses the waste heat in the scramjet cooling process as a cycle heat source and produces electric power. In this research, some of the power generated in the cycle is used to power a Polymer Electrolyte Membrane (PEM) electrolyzer that produces hydrogen. An analysis of the energy and exergy has been conducted to assess the system's performance. With a fuel mass flow rate of 0.45 kg/s, the cooling capacity of the system is 10.2 MW, net power production is 4.1 MW, and 45.1 kg/h of hydrogen is produced. The exergy analysis revealed that the PEM electrolyzer had the highest exergy loss at over 48%, followed by the first cooling path at over 32%. The energy and exergy efficiency of the system are 14.2% and 19.2%, respectively. The parametric study indicated that increasing the mass flow rate leads to higher power production and cooling capacity. Additionally, at a constant fuel mass flow rate, power production increases with higher pressure behind the pump.

Energy transfer and conversion in the Allam cycle with a multi-stream heat exchanger

The Allam cycle is renowned for its high efficiency and low emissions in power generation, utilizing supercritical carbon dioxide as the working fluid. The regenerator, one of the key heat exchangers, plays a crucial role in the system. However, modeling the regenerator is challenging due to the presence of multiple pinch points. This study proposes a regenerator model that employs three multi-stream heat exchanger modules in Aspen Plus. A thermodynamic and economic analysis of the system was conducted and compared with a conventional system utilizing the two multi-stream heat exchanger modules. Simulation results show that the combustion chamber has the highest exergy loss in the system, accounting for 46.9 % of the total exergy loss. The turbine is identified as the most capital-intensive component, representing 44.9 % of the total equipment investment. Furthermore, a sensitivity analysis was conducted on key parameters. The results indicate that under certain operating conditions, the heat provided by the air separation unit is insufficient to reduce the temperature difference at the hot outlet of the regenerator. Compared to the conventional Allam cycle system using the 2R model, the 2R model predicts deviations of up to 28.9 %. This proposed model provides a new approach for the efficient allocation of energy utilization in the multi-stream heat exchange process within the Allam cycle system.

Performance analysis of a compressed air energy storage incorporated with a biomass power generation system

Compressed air energy storage technology is recognized as a promising method to consume renewable energy on a large scale and establish the safe and stable operation of the power grid. To improve the energy efficiency and economic performance of the compressed air energy storage system, this study proposes a design for integrating a compressed air energy storage system with a biomass power generation system. In the energy storage process, the feedwater from the biomass power generation system is used to cool the compressed air in the compressed air energy storage system. In the energy release process, the flue gas from the biomass power generation system is used to heat the compressed air. Besides, the compressed air from the compressed air energy storage system first works in the expander and then goes to the biomass power generation system for combustion. Based on the system simulation, the proposed system is assessed from the energy, exergy, economy, and environment perspectives. The results show that the round-trip efficiency and the energy storage density of the compressed air energy storage subsystem are 84.90 % and 15.91 MJ/m3, respectively. The exergy efficiency of the compressed air energy storage subsystem is 80.46 %, with the highest exergy loss in the throttle valves. The total investment of the compressed air energy storage subsystem is 256.45 k$, and the dynamic payback period and the net present value are 4.20 years and 340.48 k$. Besides, the proposed system’s CO2 emission is 258 kg/GWh. This study provides a new option for enhancing the performance of compressed air energy storage through the system integration.

Comprehensive evaluation of part-load exergy performance of a supercritical carbon dioxide recompression cycle controlled by various strategies

This study seeks to provide guidance for the efficient operation of a supercritical carbon dioxide recompression cycle (sCO2-RC) by conducting a comprehensive assessment of the exergy performance under various load-following strategies. As the load decreases, we analyze the operational characteristics of the compressor and identify the components with higher irreversible proportions for the single strategy-controlled system. When the load diminishes to 10%, specific components exhibit significant irreversibility, excluding the compressor, as follows: 14.48% for the turbine under inventory control, 12.64% for the bypass mixer under turbine bypass control, and 22.10% for the bypass mixer under intermediate heat exchanger (IHX) bypass control. Owing to the compressor's near-surge operation, the turbine throttle control only minimally reduces the system load to 30%, with the throttle valve incurring the highest loss proportion of 26.33% at that point. To both ensure safe compressor operation and enhance system efficiency, auxiliary strategies such as inventory and turbine bypass are recommended to implement hybrid control. The assisted inventory improves the exergy efficiency of the system under turbine bypass control and IHX bypass control by 4.14% and 7.16% at 10% load, respectively. However, the adoption of auxiliary strategies may introduce additional losses while improving the performance of existing components. Although the assisted turbine bypass widens the adjustable load range of the turbine throttle-controlled system, it decreases the system's exergy efficiency by 3.65% at 30% load due to the introduction of a bypass mixer with higher exergy loss.

Co-gasification of biomass and plastic waste for green and blue hydrogen Production: Novel process development, economic, exergy, advanced exergy, and exergoeconomics analysis

A novel co-gasification process for biomass and plastic waste has been proposed to produce the blue and green hydrogen. For process feasibility, an Aspen Plus simulation model has been developed, and a sustainability analysis is being conducted, focusing on economic viability, exergy, advanced exergy considerations, and exergoeconomics evaluations. The current process has demonstrated economic sustainability, as evidenced by an internal rate of return (IRR) of 8 % at a process efficiency level of 70 %. The process with a waste capacity of 20 tons per hour has the potential to produce approximately 1079 kW-hours of electric power. The surplus electricity, exceeding the process requirements is utilized for green hydrogen production through an alkaline electrolysis cell (AEC). This surplus electricity has the potential to produce around 213.5 kg/day of hydrogen. The exergy analysis of this model highlights that the gasifier component exhibits the lowest exergy efficiency, resulting in the highest exergy loss, around 40 %. Furthermore, advanced exergy analysis identifies both the steam turbine and gasifier as primary sources of exergy destruction, with associated exergoeconomics costs of around $6,561.3 and $6,541.9 per hour, respectively. Consequently, improving the gasifier and steam turbine performance can enhance the overall sustainability of the process.

Designing and performance assessment of a hybrid CAES based CHP system integrated with solar energy and heat pump

In this paper, a novel combined heat and power system based on compressed air energy storage (CAES) coupled with a solar collector system was introduced. Based on the significant effect of heat pumps in improving heat quality, the heat pump and solar energy are adopted to improve energy storage and economic performance. To maximize the effective utilization of solar energy, the energy dispatch scheme of the system has been studied in detail. The system's performance under multiple operating conditions has been evaluated. Moreover, to further explore the optimization potential of the solar-coupled compressed air energy storage system, important factors such as the distribution proportion of thermal oil and key temperature have been emphasized and analyzed. The optimization of key temperature, distribution proportion of thermal oil, and operating conditions can enhance the cascade utilization of energy, and also provide a comprehensive approach for the design and optimization of the proposed system. Parametric sensitivity analysis was first conducted. Results show that the charging pressure should be close to the discharging pressure and there is no local optimal distribution ratio for the thermal oil. The optimal condition under design constraints is also determined, the system power efficiency, energy efficiency, and power-to-power efficiency reached 0.297, 0.851, and 0.570, while the levelized cost of storage of the system is 0.527 $/kWh, the dynamic payback period is 9.516 and simple payback period is 7.428 under the specified conditions. The output power and heat in 6 h of discharging are 3829.50 kWh and 7147.48 kWh, respectively, with a total investment cost of 7373.57k$. Moreover, the exergy and economic analyses were then conducted. The highest exergy losses were caused by the solar collector system with 29.01% of the total loss. The turbines and the solar system also had the highest economic cost, indicating directions for further optimization.

Thermodynamic and techno-economic analyses of hydrogen production from different algae biomass by plasma gasification

In this study, hydrogen production processes by plasma gasification of three different algae were proposed. The processes were comprehensively analyzed and evaluated in terms of thermodynamic efficiency and economic benefits. The results showed that the hydrogen production processes of Enteromorpha by plasma gasification had the best performance and the exergy efficiency of the plasma gasification was as high as 74.46%. The total efficiency of the hydrogen production process of Enteromorpha by plasma gasification was 33.92%, which was 3.87% and 3.63% higher than that of the Cyanobacteria and Sargassum process, respectively. The high exergy loss of the acid gas removal and plasma gasification unit accounted for 80.14%–83.53% of the total exergy loss. In addition, the Enteromorpha process also had better economic benefits compared to the other two processes, which was greatly affected by feedstock and electricity prices.

Exergy Analysis of Thermal Power Plant for Three Different Loads

This paper presents the energy and exergy analysis of thermal power plant Tuzla in Tuzla, Bosnia and Herzegovina. The main aim of this paper is to analyze the components of a 200 MW steam power plant unit in order to identify and quantify the sites with the highest exergy losses and to calculate exergy efficiency values of all components when operating at nominal load. The influence of the change in ambient temperature and block load on the value of exergy losses and exergy efficiency was taken into analysis. The analysis further includes the impact of steam block operation without high-pressure and low-pressure heaters on the exergy efficiency of the steam block. The goal of the analysis is to determine the functional state of individual steam block components after a long period of exploitation and maintenance in order to take appropriate measures to improve their technical performance. Exergy losses during nominal operation of the steam power plant unit are the largest in boiler and amount to 313.42 MW, followed by a turbine with 205.60 MW, condenser 1 with 6.03 MW, condenser 2 with 5.75 MW, while other components of the steam power plant have exergy losses in the range of 0.03 to 2.15 MW. Operation of the unit at nominal load without HPH results in an exergy efficiency decrease from 5.60 to 9.80 %, while in case of operation without HPH and LPH it results in a decrease in exergy efficiency from 9.86 to 16.40 % depending on the pattern used to calculate. The conclusion after the analysis indicates that the biggest exergy losses are in the boiler and turbine and consequently these components have the lowest exergy efficiency values. The increase in ambient temperature has different effects on individual components of the thermal power plant, increasing exergy losses of the boiler while reducing the turbine exergy losses and condensers.

Biomass-to-energy integrated trigeneration system using supercritical CO2 and modified Kalina cycles: Energy and exergy analysis

One of the main global challenges is to produce energy in a sustainable way, for example, from renewable energy sources. This study proposes a novel system for trigeneration of cold, heat, and electricity, driven by biomass gasifier. The proposed solution consists of a modified Kalina cycle and a supercritical CO2 power cycle. The input energy of the system is provided by the gasification of municipal solid wastes. In addition to electricity generation, the cold is produced at the sub-zero temperature in the modified Kalina cycle, and the absorbed heat is recovered by a heating unit in the supercritical CO2 cycle. The high thermal energy of the exhaust gases is used to increase the temperature of CO2 entering a gas turbine and then is directed to a boiler to run the Kalina cycle. The thermodynamic relations governing the gasifier, CO2 and Kalina cycles are developed using the engineering equation solver (EES) software. As a result of thermodynamic modeling, from 3.683 kg/s of syngas the energy and exergy efficiency at 71.45% and 55.43% can be achieved, respectively. Furthermore, the highest exergy loss is found to be 7.604 kW and 2.839 kW in the gasifier and combustion chamber, respectively.

Full-scale utilization of geothermal energy: A high-efficiency CO2 hybrid cogeneration system with low-temperature waste heat

The utilization of geothermal energy is becoming increasingly important in the current transition towards sustainable energy sources. Among the various methods of utilizing geothermal energy, the use of hybrid geothermal power plants that exploit CO2 fluid for preheating in electricity generation has been identified as an attractive approach. Additionally, the shallow ground source heat pump (SGSHP) has been proven to be superior in previous experimental studies. However, the full-scale utilization of geothermal energy, through generating electricity from geothermal power plants and applying waste heat with SGSHPs for auxiliary heating, needs further exploration. This study proposes a novel CO2 hybrid geothermal system that incorporates a GSHP heating system. The hybrid geothermal system uses CO2 as the underground working fluid, and the electricity and waste heat are used to assist the GSHP for heating, ventilation, and air conditioning. The proposed system can produce 11.41 MW of electricity, 80 °C of hot water, and 34.76 MW of cold energy by driving 50 MW of the geothermal heat. Through a comprehensive analysis of the economy, energy, exergy, and environment, the results demonstrate that the maximum exergy damage of the refrigeration power cycle is 37999.33 kW, which has the highest exergy losses. The exergy loss of the steam turbine heat power conversion in the geothermal power generation process is the highest, but this loss can be effectively reduced through heat integration. The optimal cooling temperature of the coupled system should be set at 8 °C, and it has a good investment prospect. In summary, the CO2 hybrid geothermal system can realize effective cogeneration and fully utilize geothermal energy. Therefore, it has great potential to contribute to the transition towards a sustainable energy future.

Energy, exergy, energy-saving, economic and environmental analysis of a micro-gas turbine-PV/T combined cooling, heating and power (CCHP) system under different operation strategies: Transient simulation

A micro-gas turbine (MGT) combined cooling, heating and power system coupled with low concentrating photovoltaic/thermal-heat hump (LCPV/T-HP) and absorption chiller is proposed in this study. LCPV/T is used as the heat source of HP to realize mutual promotion. The performance of CCHP system under different operation strategies is dynamically simulated and analyzed by TRNSYS software from energy, exergy, energy-saving, economy and environment. The results demonstrate that both high temperature water source heat pump (HWHP) and low temperature water source heat pump (LWHP) achieved better COP in following electric load (FEL) mode. The average COP of HWHP and LWHP are 22.69% and 4.75% higher than the rated COP, respectively. Annual total cost per unit building area (ATCUBA) and carbon dioxide emissions per unit building area (CDEUBA) are also more advantageous in FEL mode, while primary energy consumption per unit building area (PECUBA), ATCUBA and CDEUBA seems less preferable in following thermal load (FTL) mode. The exergy efficiency and energy efficiency of the system in FEL mode are 19.96% and 41.90% in summer, and 25.13% and 59.36% in winter. Additionally, the equipment with higher exergy loss is mainly LCPV/T, gas-fired boiler, absorption refrigeration unit, MGT and hot water generator under the three operation strategies.

Process optimization and thermodynamic analysis of autothermal coal chemical looping gasification industrial demonstration system

Chemical looping gasification (CLG) is an innovative clean coal conversion technology with industrial application prospects. The technical reliability of coal CLG (CCLG) in an autothermal state remains to be investigated. To clarify the process characteristics of an autothermal CCLG process, a CCLG autothermal operation system was established based on a CLG industrial demonstration unit. Process modeling of the CCLG reactor system and economizer, air preheater, and other heat exchange units was performed, to ensure autothermal operation of the global CCLG process. The optimal operating parameters of the system were established, the optimal heat exchange network was designed, and the source and distribution of thermodynamic irreversibility were clarified. The results showed that the optimal coal feed flow rate, air feed temperature and flue gas circulation temperature were 437.07 kg/h, 550 °C and 450 °C, respectively. The fuel reactor (FR) flue gas circulation was not conducive to system autothermal, resulting in weakened gasification performance. The optimal heat exchange plan allowed the system to operate without an external heat source. The thermodynamic irreversibility mainly originated from the redox process. The system heat efficiency was 81.63 %, the product exergy efficiency was 78.06 %, the total exergy efficiency was 41.10 %, and the total exergy destruction rate was 55.40 %. Additionally, the FR flue gas circulation caused high exergy loss, resulting in reduced system thermodynamic efficiency.

Energy and exergy analysis of Derna steam power plant and the impact of varying the different parameters on exergy destruction

In this study, an energy and exergy analysis of the Derna steam power plant in Libya is presented. This study aims to identify the components with high energy and exergy losses which are leading to a decrease in the performance of the power plant. The largest place losses can be figured out hence to subsequently ensure where the greatest margin for improvement would be incurred. The influence of different parameters, such as temperatures and pressure values, on this analysis, is also conducted via the so-called Engineering Equation Solver software (EES). In terms of energy, the condenser is found to majorly have the highest energy losses of approximately 103MW which is received by the environment whilst the boiler losses are recorded to be about 24MW. As far as exergy is concerned, the boiler system is found to have the highest percentage ratio of exergy destruction to overall exergy destruction of 88 %, followed by the turbine of 8% and then the condenser of 3%. In addition, the thermal efficiency is also calculated based on the lower heating value of fuel and found to be 29% whereas the exergy efficiency of the power cycle is then computed to be 27.19%. The study is further concluded the significant effect of the live steam temperature changes concerning the design value, the high pressure heater (HPH) pressure as well as the condenser pressure on exergy destruction.

Introducing and assessment of a new wind and solar-based diversified energy production system intergrading single-effect absorption refrigeration, ORC, and SRC cycles

This paper proposes and evaluates an integrated energy production system using two forms of renewable energy, solar and wind, in order to deliver cooling, heating, electricity, and water desalination. Along with organic Rankine cycle components (ORC), this diversified energy system includes an absorption refrigeration system, steam Rankine cycle (SRC), thermoelectrics, reverse osmosis, wind turbines, and parabolic-linear solar collectors. This study contains several innovations, including using thermoelectrics in the Rankine organic cycle instead of a condenser that gives the system a high capacity, utilizing parabolic solar collectors, and implementing wind energy as the direct source of electricity for such system. Energy, Exergy, and Exergoeconomic analysis approach is performed for the evaluation approach. EES software is used to model and analyze the data. As part of the validation process, the results are compared with those published previously and are found to be relatively consistent. The research results revealed four points. First, with the increase in solar radiation, the amount of freshwater produced for the system increased from 69.15 to 75.23 m3/h. Second, the total exergy efficiency increased from 54.24 to 77.27% when the steam turbine's inlet pressure was increased. Third, the system's total cost decreased from 77.27 to 28.30 $/h with increasing ambient temperature. Fourth, the highest exergy loss is associated with solar energy with a central receiver. Based on exergy losses, it was determined that a solar system with 60% and a wind turbine with 17% have the highest losses.

Energy and exergy analysis of three leaved yam starch drying in a tray dryer: parametric, modelling and optimization studies

Engineering conservation during the drying process is paramount as it will help in the preservation and cost minimization of food products during processing to avoid spoilage and maximize their utilization in society. Unlike other yam species, three-leaved yam starch (TLYS) contains phytonutrients for the treatment of ailments such as diabetes and rheumatism. This work examined the energy and exergy of TLYS drying. The starch was extracted from the tuber and dried while the temperature, time, air velocity, and sample thickness were varied. TLYS proximate and SEM analysis revealed a significant amount of starch. Energy analysis revealed that energy utilization (EU) and energy utilization ratio (EUR) increased as the temperature rose and decreased as drying time increased; energy efficiency (EE) increased steadily and then reduced as drying time increased. Exergy analysis revealed that drying temperature increased exergetic efficiency and loss; drying time increased exergetic efficiency from 30 min to 4 h. The highest exergy loss was observed when the sample was dried for 4 h and the thickness is 17 mm; as the thickness decreased to 12.75 mm, the exergy loss decreased from 2.471392 J/s to 1.459247 J/s; the highest exergy efficiency of 2.471392 J/s was observed at the thickness of 4.25 mm, and the sustainability index increased as the sample thickness increased and decreased as the drying air temperature decreased. Response surface methodology (RSM) was utilized to model and optimize the effect of the process’s inherent operating factors (temperature, time, and air velocity) and maximize the process’s energy and exergy efficiency. The (Analysis of Variance) ANOVA revealed a second-order polynomial model with an R2 (0.9911), Adj R2 (0.9797) and Pred R2 (0.8577) for energy efficiency and R2 (0.9824), Adj R2 (0.9598), and Pred R2 (0.7184) for exergy efficiency, indicating a significant correlation between observed and predicted values. At a temperature of 60 °C, a time of 3 h, and an air velocity of 1.5 m/s, the optimal energy efficiency of 75.09 % and exergy efficiency of 99.221% were obtained with desirability of 0.997. The findings of this study can be used to improve the design and development of driers for TLYS preservation.

Exergy analysis of banana drying process via a closed-loop air source heat pump system

ABSTRACT In this study, an air source heat pump drying system with an external condenser circuit connected in series was developed. The system was designed to enable the external condenser to be activated serially with the internal one via the solenoid valves controlled by the digital thermostat when the drying temperature of the cabinet reaches the desired level. Temperature control of the drying chamber was achieved by activating the external condenser along with the internal condenser. Exergy analysis was conducted for the process of drying banana slices via a closed-loop air source heat pump dryer (HPD) at various drying temperatures. Exergy efficiencies and losses for the HPD system were calculated. As a result, the exergy efficiency of the dryer was calculated to be between 75.93% and 80.95%, while the exergy efficiencies of the system and heat pump were found to range from 7 to 13.07%. Moreover, the expansion valve was found to have the highest exergy efficiency with 93.32%. The highest exergy losses were also found in the compressor and condenser with 0.557 kW and 0.366 kW, respectively.

Experimental analysis of the effects of climate conditions on heat pump system performance

In this study, it was aimed to reveal the energy and exergy losses caused by air temperature and water vapor in the air, which are the most important elements of climatic conditions, in heating-cooling processes and in the operation of the heat pump system. Two water source heat pumps were used in the system established for the experimental analysis. The relative humidity and temperature of the atmospheric air were reduced with the first heat pump. Relative humidity levels of 30%, 40%, 50%, 60%, 70%, 80%, 90%, respectively, were provided to the air brought to 20 °C, 23 °C, 26 °C, 29 °C, 32 °C temperature levels in the system. The effects of the air reaching the desired humidity and temperature on the 2nd heat pump were determined with temperature, humidity, pressure, flow and ampermeters for air, water and refrigerant. The results were subjected to thermodynamic calculations and presented graphically. This experimental studies done revealed that water vapor (relative humidity) in the air increases the exergy destruction on heating and cooling works. It was revealed that the heat pump components, especially the evaporator, suffer high exergy losses. With the increase of relative humidity, exergy and energy losses in heat pumps and each of their components also increase. In this study, it was revealed that the heating and cooling works became more difficult with the increase of water vapor in the air. Accordingly, it was observed that the heat pump system elements can be operated in different styles and capacities in high humidity areas.

Exergetic analysis of hydrogen utilisation pathways – Part 1: Energy supply in buildings

This article analyses exergy losses along hydrogen utilisation pathways recently discussed in Germany and other countries. As a renewable fuel hydrogen will be an important part of sustainable future economies. Hydrogen can be used in all sectors, especially in buildings, for mobility and in industry, e.g. in steel production or ammonia synthesis. However, hydrogen has to be produced in a sustainable way. The most promising production is via water electrolysis using renewable electricity. In the first part of this work, exergy analysis is made for the complete hydrogen pathways from production until final utilisation for energy supply in buildings. The second part will focus on pathways for mobility. In the third part, the results are compared with available alternatives to hydrogen such as direct use of electricity in building supply or mobility. The results for building energy supply show that firstly transportation in pipelines (mixture with natural gas and pure hydrogen) is very efficient. Secondly, major exergy losses are caused by the electrolyser. Thirdly, combustion of renewable hydrogen for room heating in common boilers cause the highest exergy losses, but the use of combined heat and power (CHP) units or fuel cells can improve the exergy efficiency substantially.

Exergoeconomic and exergoenvironmental assessment of a PV/T assisted wastewater source heat pump system for a sustainable future

This paper investigated exergetic, exergoeconomical and exergoenvironmental performances of a photovoltaic/thermal (PV/T) assisted wastewater source heat pump (WWSHP) system. The highest relative irreversibility among all the components occurred in the PV/T unit, followed by the compressor. The functional exergy efficiencies of the WWSHP and whole system were found to be 0.10 and 0.15, respectively. The exergoeconomic factors of the condenser and wastewater heat exchanger were determined to be considerably high among all the components. The highest exergy loss per unit price was due to the PV/T system. Exergoeconomic factors for each equipment and the entire system decreased with increasing yearly working period and decreasing interest rate. The same trend was also observed in the specific cost of exergetic product. Exergy destruction related environmental impacts were found to be the major element in almost all of the components and therefore its reduction should be the main focus on exergoenvironmental performance improvements.