Performance analysis of cogeneration systems based on micro gas turbine (MGT), organic Rankine cycle and ejector refrigeration cycle

Abstract

In this paper, the operation performance of three novel kinds of cogeneration systems under design and off-design condition was investigated. The systems are MGT (micro gas turbine) + ORC (organic Rankine cycle) for electricity demand, MGT+ ERC (ejector refrigeration cycle) for electricity and cooling demand, and MGT+ ORC+ ERC for electricity and cooling demand. The effect of 5 different working fluids on cogeneration systems was studied. The results show that under the design condition, when using R600 in the bottoming cycle, the MGT+ ORC system has the lowest total output of 117.1 kW with a thermal efficiency of 0.334, and the MGT+ ERC system has the largest total output of 142.6 kW with a thermal efficiency of 0.408. For the MGT+ ORC+ ERC system, the total output is between the other two systems, which is 129.3 kW with a thermal efficiency of 0.370. For the effect of different working fluids, R123 is the most suitable working fluid for MGT+ ORC with the maximum electricity output power and R600 is the most suitable working fluid for MGT+ ERC with the maximum cooling capacity, while both R600 and R123 can make MGT+ ORC+ ERC achieve a good comprehensive performance of refrigeration and electricity. The thermal efficiency of three cogeneration systems can be effectively improved under off-design condition because the bottoming cycle can compensate for the power decrease of MGT. The results obtained in this paper can provide a reference for the design and operation of the cogeneration system for distributed energy systems (DES).

Keywords

cogeneration system / different working fluids / micro gas turbine (MGT) / organic Rankine cycle (ORC) / ejector refrigeration cycle (ERC)

Introduction

The micro gas turbine (MGT) has been widely applied in the distributed energy system (DES) because of its famous merits of fuel flexibility [¹–³]. Usually, the exhaust gas temperature from MGT is in the range of 250°C–300°C. To make full use of the exhaust heat, a bottoming cycle such as organic Rankine cycle (ORC) or ejector refrigeration cycle (ERC) is combined to improve the comprehensive utilization of energy. The ORC system is widely used for the medium and low temperature heat source due to the low boiling point of working fluid. It has the advantage of selecting the most suitable working fluid for the corresponding heat source temperature [⁴–⁶]. ERC can also operate with organic working fluid suitable for medium and low temperature heat sources [⁷]. It has several advantages such as a simple structure, a low installation price, and a low maintenance cost. Therefore, the above mentioned methods have attracted much attention from researchers in recent years.

The performance analysis and optimization of the MGT and ORC cogeneration has been researched recently. Mago and Luck [⁸] proposed a reheat type ORC system to recycle MGT waste heat using R113, R245fa, R123, and R236fa. The result showed that the thermal efficiency of the combined system was improved with an average efficiency increase of 27%. Srinivasan et al. [⁹] proposed an ORC system as the bottoming cycle of the turbocharger system to recycle the waste heat, and the result showed that the fuel conversion efficiency was effectively improved. Guillaume et al. [¹⁰] recommended a radial-inflow turbine integrated in an ORC system for a WHR on truck application using R245fa and R1233zd. The result showed that R1233zd represented a better choice compared to R245fa. Mandal et al. [¹¹] optimized the GT and ORC combined system with multiple objective optimization considering compression ratio, efficiency, inlet temperature, evaporation temperature and other parameters. The result showed that the turbine inlet temperature played an important role in exergy efficiency and operating cost. Sung et al. [¹²] conducted an economic analysis of biomass gas MGT and ORC combined system to validate that the ORC can improve the economic performance. Yari [¹³] proposed the ORC to recycle MGT waste heat using an internal heat exchanger. The result showed that the turbine inlet temperature, pressure ratio, evaporation temperature, pinch temperature had a significant effect on system performance. Benato et al. [¹⁴] investigated the working fluid selection of the ORC for 65 kW waste heat recovery system. The result showed that the cyclohexane had a relatively good performance. Amirante et al. [¹⁵] compared the steam system and the ORC system for the 30 kW turbocharger waste heat recovery and the result showed that the ORC system was more efficient than the steam system. Clemente et al. [¹⁶] investigated the bottoming cycle for recycling waste heat from the 100 kW MGT system, demonstrating the effect of 6 working fluids on the bottoming cycle performance. Jradi and Riffat [¹⁷] analyzed the overall-load performance of a MGT+ ORC cogeneration system with an efficiency of up to 40%. The result showed that the speed control method was better than the fuel control method, and R123 was more efficient than steam. However, the aforementioned references only considered the power generation, which did not mention the refrigeration for the DES.

To meet the demand diversity of the DES, the ERC is also adopted as the bottoming cycle of the cogeneration system. Ebrahimi and Majidi [¹⁸] conducted an optimization for the cogeneration cycle of MGT and ERC based on energy efficiency and exergy efficiency. The result showed that the overall energy and exergy efficiencies are about 56% and 69%. Boumaraf et al. [¹⁹] proposed a novel ejector refrigeration configuration of two evaporators and a throttle valve in order to overcome the operation limitation of the separator in the traditional ERC. The result showed that the configuration can improve the COP of ERC for both R134a and R1234yf. The combination of ORC and ERC could enable the cogeneration system to provide electricity power and cooling capacity. Ebrahimi and Ahookhosh [²⁰] also proposed a novel cogeneration for cooling/heating and power which comprised of MGT, ORC, ERC, and heat recovery equipment. They conducted the integrated energy-exergy optimization to obtain the optimum operation condition for summer and winter with an energy saving of 37% and 24% respectively. Zheng and Weng [²¹] put forward a kind of cooling-power cogeneration which used the exhaust vapor to drive the ejector refrigeration. The result showed that the thermal efficiency could reach 15.6% with an exergy efficiency of up to 37.5% at an evaporation temperature of 120°C, a refrigeration evaporation temperature of 7°C, and a condensing temperature of 25°C. Therefore the ERC and its combination with ORC were promising as the bottoming cycle for the cogeneration system.

However, the above researches only focused on the single cogeneration system. This paper studied three cogeneration systems of MGT+ ORC, MGT+ ERC, and MGT+ ORC+ ERC based on MGT, ORC, and ERC respectively. The effect of different working fluids on the cogeneration system performance was researched and the off-design performance of the cogeneration systems was investigated which provided a reference for the development of the cogeneration system for DES.

Configuration and modeling method for cogeneration system

Configuration

The cogeneration systems of MGT+ ORC, MGT+ ERC, and MGT+ ORC+ ERC are shown in Fig. 1. The MGT+ ORC can satisfy the electricity demand of the consumer. The MGT+ ERC can satisfy both the electricity and cooling demand with the bottoming ERC providing cooling output. The MGT+ ORC+ ERC can also satisfy both the electricity and cooling demand with the bottoming cycle providing electricity and cooling output simultaneously.

The MGT is the main component and operates as the top cycle of the cogeneration systems. The ORC consists of a working fluid pump, an evaporator, a turbine, a condenser, and a liquid storage tank. As shown in Fig. 1(a), the organic working fluid pressurized by the working fluid pump absorbs heat in the evaporator from the exhaust gas, then generates organic vapor. The organic vapor drives the turbine to provide output power externally.

The ERC is composed of a refrigerant pump, an evaporator, an ejector, a condenser, a refrigeration evaporator, and a liquid storage tank. As shown in Fig. 1(b), the working vapor generated inside the evaporator enters the ejector and produces an ejection effect at the nozzle exit in the receiving chamber, which drives the refrigeration evaporator to provide cooling capacity externally. The refrigeration vapor is mixed with the working vapor in the mixing chamber before entering the condenser.

As shown in Fig. 1(c), the ORC+ ERC system is similar to the ORC system as described above, except for the fact that the exhaust vapor from the turbine still has a relatively high pressure and temperature, which continues to flow into the ejector as working vapor to drive the refrigeration evaporator.

Modeling methods

The thermodynamic models of the MGT, ORC, and ERC were established respectively, which were described in detail in Refs. [²¹–²³]. The MGT model mainly includes the mathematical formula, operation parameters of compressor, turbine, regenerator, and combustion chamber. The off-design models of MGT are mainly based on the performance curves of the compressor and turbine. The ORC model mainly includes the mathematical formula, operation parameters of evaporator, working fluid pump, turbine, and condenser. The e-NTU method is adopted for the off-design modeling of the evaporator. The evaporation temperature and working fluid mass flow rate are optimized to obtain the maximum output power. The off-design performance parameters of the radial turbine in the bottoming cycle are calculated based on the performance curve of the organic working fluid radial turbine. For the ERC model, the ejector model based on the one-dimensional aerodynamic calculation method can be adopted to calculate the off-design performance at the corresponding working pressure. Then the mathematical models of three cogeneration systems were established correspondingly.

The pinch point method was adopted for the calculation of the heat transfer process in the evaporator. The heat exchange process is demonstrated in Fig. 2. The minimum temperature difference between the exhaust gas and working fluid is called the pinch point temperature difference. The pinch point is usually obtained at the bubble point of the working fluid.

Performance analysis under design condition

Based on the above thermodynamic models, the performance analysis of three kinds of cogeneration systems was conducted respectively under design condition.

The design parameters of the three cogeneration systems were listed in Table 1. For the bottoming cycle, R600 is selected as the design working fluid due to the good comprehensive performance of the thermodynamic property, environmental impacts, and safety as recommended in Ref. [²³].

The thermodynamic parameters were calculated as tabulated in Table2. Node 10 in MGT+ ORC represents the outlet of the radial turbine with an exhaust temperature of 72.3°C. Node 10 in MGT+ ERC represents the outlet of the ejector with an exhaust temperature of 84.2°C while Node 9 in MGT+ ORC+ ERC represents the interface between the radial turbine and the ejector with a temperature of 122.2°C and a pressure of 2054.4 kPa. The expansion ratio of the expander in this cogeneration system is selected as half of the design value compared with the separate ORC system. It is obvious that the MGT+ ORC+ ERC system sacrifices a portion of the power generation capability to provide the working vapor for the ERC.

The performance parameters were obtained as presented in Table 3.The equivalent thermal energy method is usually used for the evaluation of electricity and cooling capacity, so the output of the cooling capacity is judged as equivalent thermal energy according to 1:1. The total thermal efficiency of the cogeneration is evaluated by the ratio of output of electricity and cooling capacity to the energy input of fuel gas [²⁴]. The total output of the MGT+ ORC system is 117.1 kW with a thermal efficiency of 0.334. The total output of the MGT+ ERC system is 142.6 kW with a thermal efficiency of 0.408, and the total output of the MGT+ ORC+ ERC system is 129.3 kW with a thermal efficiency of 0.370.

Therefore, the MGT+ ORC cogeneration system is suitable for the occasion with more electricity demand although it has the lowest total output. The MGT+ ERC cogeneration system has the largest total output including electricity and cooling capacity which is suitable for the occasion with more cooling demand. The total output of the MGT+ ORC+ ERC cogeneration system is between the other two systems.

Performance analysis for different working fluids

To study the matching regulation of the working fluid in the bottoming cycle and the cogeneration system, the performance of the cogeneration systems under design condition was investigated using R600, R123, R245fa, R601a, and R600a.

MGT+ ORC

The performance parameters of the MGT+ ORC cogeneration system were obtained as given in Table 4. The evaporation temperature for different working fluids was selected according to their critical temperature in order to ensure the subcritical working condition. The maximum evaporation temperature of the evaporator near the critical temperature of each working fluid was selected as the design condition in order to achieve the maximum output power from the exhaust gas. R601a has the maximum evaporation temperature, followed by R123.R245fa and R600 have the medium evaporation temperature, while R600a has the minimum evaporation temperature.

R123 has the maximum output power for the cogeneration system, followed by R601a. R245fa and R600 have the medium output power, while the output power for R600a is the minimum. The working fluid with a higher critical temperature can provide a higher output power and efficiency of ORC such as R123 and R601a. For instance, the output power of the cogeneration system is 120.9 kW for R123 with a thermal efficiency of 0.345, while the output power is 114.7 kW for R600a with a thermal efficiency of 0.328. In addition, the thermal efficiency of ORC using R245fa is in accordance with the result in Ref. [²⁵].

MGT+ ERC

The performance parameters of the MGT+ ERC cogeneration system were obtained as shown in Table 5. The evaporation temperature is the same as that of the ORC for each working fluid.

As can be observed in Table 5, R600 has the maximum cooling capacity output, followed by R600a while R123 and R601a have a relatively medium cooling capacity output. R245fa has the minimum cooling capacity of the 5 working fluids. The working fluid with a higher ejection coefficient and enthalpy variation can provide a higher cooling capacity such as R600 while the working fluid with a lower ejection coefficient and enthalpy variation provides a lower cooling capacity such as R245fa. For instance, the total output of the cogeneration system is 142.6 kW for R600 with a thermal efficiency of 0.408, while the total output is 132.1 kW for R245fa with a thermal efficiency of 0.378. In addition, the ejector coefficient of ERC using R600a is in accordance with the variation range in Ref. [²¹] which can help validate the rationality of the results obtained in this paper.

MGT+ ORC+ ERC

The performance parameters of the MGT+ ORC+ ERC cogeneration system were obtained as shown in Table 6. The evaporation temperature is the same as that of the separate ORC and ERC cycle for each working fluid.

It is apparently seen that R123 and R600 have a good comprehensive performance of electricity and refrigeration due to the combination of the advantage of separate power generation capability and refrigeration capacity in the MGT+ ORC+ ERC cogeneration system, followed by R601a. The total output of R600a is medium while R245fa exhibits the minimum total output. For instance, the total output of the cogeneration system is 129.7 kW for R123 with a thermal efficiency of 0.371 while the total output of the cogeneration system is 122.3 kW for R245fa with a thermal efficiency of 0.349.

Performance comparison of the three cogeneration systems

The performance parameters of the three cogeneration systems using different working fluids under design condition are obtained and listed in Table 7.

For all working fluids, the MGT+ ERC cogeneration system has the largest total output and thermal efficiency, and the MGT+ ORC cogeneration system has the lowest total output and thermal efficiency, while the total output and thermal efficiency of MGT+ ORC+ ERC are within the other two systems. R123 is the most suitable working fluid for MGT+ ORC with the maximum power generation capability of ORC. R600 is the most suitable working fluid for MGT+ ERC with the maximum cooling capacity of ERC. Both R600 and R123 can make MGT+ ORC+ ERC achieve a good comprehensive performance of refrigeration and electricity.

Performance analysis under off-design condition

The off-design performance of the three cogeneration systems was investigated in order to evaluate the operation feasibility. The off-design analysis of cogeneration includes many parameters and variables such as the rotation speed, pressure ratio, fuel-air ratio of the micro gas turbine. This paper mainly focus on the variation of performance of cogeneration systems with the variable fuel mass flow rate of MGT.

MGT+ ORC

Figure 3 depicts the variation of the output power of ORC for different working fluids, fuel gas mass flow rate, and exhaust gas temperature of MGT under off-design condition of the MGT+ ORC cogeneration system. The exhaust gas temperature decreases from 300°C to 240°C as the output power decreases from 100 kW to 47 kW. The fuel gas mass flow rate decreases from 0.0076 kg/s to 0.0059 kg/s. The ORC output power decreases with the exhaust gas temperature decreasing. For instance, the output power of ORC decreases from 20.9 kW to 12.5 kW for R123 with the exhaust gas temperature decreasing. Consistent with the previous statement, R123 generates the maximum output power during the range of operating conditions, followed by R601a. R245fa, and R600 rank medium. R600a has the minimum output power for the cogeneration system.

Figure 4 exhibits the variation of the total output power, thermal efficiency and ORC efficiency contribution of the MGT+ ORC cogeneration system. The total output power of the MGT+ ORC cogeneration system decreases, which is determined both by the reduced output power of the MGT and ORC. For instance, the total output power of the cogeneration system decreases from 120.9 kW to 59.7 kW when R123 is used in the bottoming ORC cycle. The thermal efficiency of the cogeneration system decreases from 34.5% to 22.6%, while for R600a, the total output power of the cogeneration system drops from 114.7 kW to 55.9 kW, and the thermal efficiency is reduced from 32.8% to 20.8%. However, the ORC efficiency contribution for different working fluids just decreases slightly. For instance, the efficiency contribution of ORC for R123 decreases slightly from 5.9% to 5.2%. The reason for this is that the output power of ORC can compensate for the power decrease of MGT with the corresponding reduced fuel mass flow rate under off-design condition.

MGT+ ERC

Figure 5 shows the variation of the cooling capacity of ERC for different working fluids, fuel gas mass flow rate, and MGT exhaust gas temperature. The cooling capacity of ERC decreases as the exhaust gas temperature decreasing. For R600, the cooling capacity of ERC decreases from 42.6 kW to 28.9 kW with the exhaust gas temperature decreasing. Consistent with the previous statement, R600 has the maximum cooling capacity in the range of operating conditions, followed by R600a. R123 and R600 have the medium cooling capacity while R245fa has the minimum cooling capacity.

Figure 6 displays the variation of the total output, thermal efficiency, and ERC efficiency contribution of the MGT+ ERC cogeneration system. The total output of the cogeneration system decreases, which is determined by the reduction of the output power of MGT and the cooling capacity of ERC. For instance, the total output of the cogeneration system for R600 decreases from 142.6 kW to 75.9 kW. In the meantime, the thermal efficiency decreases from 40.8% to 28.1% while for R245fa, the total output of the cogeneration system drops from 132.1 kW to 68.1kW and the thermal efficiency is reduced from 37.8% to 25.5%. However, the efficiency contribution of ERC for different working fluids just decreases slightly. For instance, the efficiency contribution of ERC for R600 only drops slightly from 12.1% to 10.6%. This is because the cooling capacity of ERC can compensate for the power decrease of MGT with the corresponding reduced fuel mass flow rate.

MGT+ ORC+ ERC

Figure 7 shows the variation of the total output of ORC+ ERC for different working fluids, fuel gas mass flow rate, and MGT exhaust gas temperature. The total output of ORC+ ERC decreases as the exhaust gas temperature decreasing. For R123, the total output of ORC+ ERC decreases from 29.7 kW to 20.4 kW. Consistent with the previous statement, R123 and R600 both exhibit a relatively larger total output within the range of off-design conditions, followed by R601a. R600a has a medium total output while R245fa has the minimum total output.

Figure 8 shows the variation of the total output, thermal efficiency and ORC+ ERC efficiency contribution of the MGT+ ORC+ ERC cogeneration system. The total output of the MGT+ ORC+ ERC cogeneration system decreases, which is determined by the reduced output power of the MGT and the total output of the ORC+ ERC cycle. For instance, the total output of the cogeneration system for R123 decreases from 129.7 kW to 67.4 kW. In the meantime, the thermal efficiency of the cogeneration system decreases from 37.1% to 25.0%. For R245fa, the total output of the cogeneration system decreases from 122.3 kW to 61.6 kW with the thermal efficiency decreasing from 34.9% to 23%. However, the ORC+ ERC efficiency contribution of the MGT+ ORC+ ERC cogeneration system for different working fluids just decreases slightly. For instance, the ORC+ ERC efficiency contribution for R245fa decreases from 6.2% to 5.5%. The reason for this is that the total output of ORC+ ERC can compensate for the power decrease of MGT with the corresponding reduced fuel mass flow rate.

Conclusions

This paper has proposed three novel cogeneration systems including MGT+ ORC for electricity demand, MGT+ ERC for electricity and cooling demand, and MGT+ ORC+ ERC for electricity and cooling demand. The performance of three kinds of cogeneration systems was compared and the off-design performance of the cogeneration systems was investigated for 5 different working fluids. The results show that under design condition, the MGT+ ERC cogeneration system can provide the largest total output of 142.6 kW with a thermal efficiency of 40.8% which is suitable for the occasion with more cooling demand. The MGT+ ORC cogeneration system has the minimum total output of 117.1 kW with a thermal efficiency of 0.334 which is suitable for the occasion with electricity demand. The total output of the MGT+ ORC+ ERC is between the other two systems which is 129.3 kW with a thermal efficiency of 0.370.

R123 is the most suitable working fluid for MGT+ ORC with the maximum power generation capability of ORC. R600 is the most suitable working fluid for MGT+ ERC with the maximum refrigeration capacity of ERC. Both R600 and R123 make the MGT+ ORC+ ERC system achieve good comprehensive performance of refrigeration and electricity.

The total output and thermal efficiency of three kinds of cogeneration systems decrease when deviating from the design condition. However, the bottoming cycle efficiency contribution of the three cogeneration systems can maintain a stable level with a slight reduction under off-design condition, which indicates that the bottoming cycle can compensate for the power decrease of MGT with the corresponding reduced fuel mass flow rate.

References

[1] Han J, Ouyang L, Xu Y, Zeng R, Kang S, Zhang G. Current status of distributed energy system in China. Renewable & Sustainable Energy Reviews, 2016, 55: 288–297

[2] Olumayegun O, Wang M, Kelsall G. Closed-cycle gas turbine for power generation: a state-of-the-art review. Fuel, 2016, 180: 694–717

[3] Wee J H. Molten carbonate fuel cell and gas turbine hybrid systems as distributed energy resources. Applied Energy, 2011, 88(12): 4252–4263

[4] Invernizzi C, Iora P, Silva P. Bottoming micro-Rankine cycles for micro-gas turbines. Applied Thermal Engineering, 2007, 27(1): 100–110

[5] Lee J H, Kim T S. Analysis of design and part load performance of micro gas turbine/organic Rankine cycle combined systems. Journal of Mechanical Science and Technology, 2006, 20(9): 1502–1513

[6] Camporeale S M, Pantaleo A M, Ciliberti P D, Fortunato B. Cycle configuration analysis and techno-economic sensitivity of biomass externally fired gas turbine with bottoming ORC. Energy Conversion and Management, 2015, 105: 1239–1250

[7] Chen J, Havtun H, Palm B. Screening of working fluids for the ejector refrigeration system. International Journal of Refrigeration, 2014, 47: 1–14

[8] Mago P J, Luck R. Energetic and exergetic analysis of waste heat recovery from a microturbine using organic Rankine cycles. International Journal of Energy Research, 2013, 37(8): 888–898

[9] Srinivasan K K, Mago P J, Krishnan S R. Analysis of exhaust waste heat recovery from a dual fuel low temperature combustion engine using an organic Rankine cycle. Energy, 2010, 35(6): 2387–2399

[10] Guillaume L, Legros A, Desideri A, Lemort V. Performance of a radial-inflow turbine integrated in an ORC system and designed for a WHR on truck application: an experimental comparison between R245fa and R1233zd. Applied Energy, 2017, 186: 408–422

[11] Mondal P, Mondal K, Ghosh S. Bio-gasification based distributed power generation system employing indirectly heated GT and supercritical ORC: energetic and exergetic performance assessment. International Journal of Renewable Energy Research, 2015, 5(3): 773–781

[12] Sung T, Kim S, Kim K C. Thermoeconomic analysis of a biogas-fueled micro-gas turbine with a bottoming organic Rankine cycle for a sewage sludge and food waste treatment plant in the Republic of Korea. Applied Thermal Engineering, 2017, 127: 963–974

[13] Yari M. Thermodynamic analysis of a combined micro turbine with a micro ORC. In: Proceedings of the ASME Turbo Expo, Berlin, Germany, 2008: 797–805

[14] Benato A, Stoppato A, Mirandola A, Del Medico M. Design and Off-design analysis of an ORC coupled with a micro-gas turbine. Energy Procedia, 2017, 129: 551–558

[15] Amirante R, Palma P O, Distaso E, Pantaleo A M, Tamburrano P. Thermodynamic analysis of a small scale combined cycle for energy generation from carbon neutral biomass. Energy Procedia, 2017, 129: 891–898

[16] Clemente S, Micheli D, Reini M, Taccani R. Bottoming organic Rankine cycle for a small scale gas turbine: a comparison of different solutions. Applied Energy, 2013, 106: 355–364

[17] Jradi M, Riffat S. Modelling and testing of a hybrid solar-biomass ORC-based micro-CHP system. International Journal of Energy Research, 2014, 38(8): 1039–1052

[18] Ebrahimi M, Majidi S. Exergy-energy-environ evaluation of combined cooling heating and power system based on a double stage compression regenerative gas turbine in large scales. Energy Conversion and Management, 2017, 150: 122–133

[19] Boumaraf L, Haberschill P, Lallemand A. Investigation of a novel ejector expansion refrigeration system using the working fluid R134a and its potential substitute R1234yf. International Journal of Refrigeration, 2014, 45: 148–159

[20] Ebrahimi M, Ahookhosh K. Integrated energy-exergy optimization of a novel micro-CCHP cycle based on MGT-ORC and steam ejector refrigerator. Applied Thermal Engineering, 2016, 102: 1206–1218

[21] Zheng B, Weng Y W. A combined power and ejector refrigeration cycle for low temperature heat sources. Solar Energy, 2010, 84(5): 784–791

[22] Zhang Q, Bo Z M, Sang Z K, Weng Y W. Analysis on operating characteristics of biogas-fired micro gas turbine. Journal of Engineering for Thermal Energy and Power, 2016, 31(3): 44–49 (in Chinese)

[23] Wang Y P, Liu X, Ding X Y, Weng Y W. Experimental investigation on the performance of ORC power system using zeotropic mixture R601a/R600a. International Journal of Energy Research, 2017, 41(5): 673–688

[24] Du Y, Dai Y P. Off-design performance analysis of a power-cooling cogeneration system combining a Kalina cycle with an ejector refrigeration cycle. Energy, 2018, 161: 233–250

[25] Caresana F, Comodi G, Pelagalli L. Micro combined plant with gas turbine and organic cycle. In: Proceedings of the ASME Turbo Expo, Berlin, Germany, 2008: 787–795

RIGHTS & PERMISSIONS

Higher Education Press and Springer-Verlag GmbH Germany, part of Springer Nature