Energy and exergy analyses of a novel cogeneration system coupled with absorption heat pump and organic Rankine cycle based on a direct air cooling coal-fired power plant

Energy ◽  
2021 ◽  
Vol 229 ◽  
pp. 120641
Author(s):  
Hongsheng Zhang ◽  
Xingang Liu ◽  
Yifeng Liu ◽  
Chenghong Duan ◽  
Zhan Dou ◽  
...  
Entropy ◽  
2018 ◽  
Vol 20 (7) ◽  
pp. 484 ◽  
Author(s):  
Mohammad Ahmadi ◽  
Mirhadi Sadaghiani ◽  
Fathollah Pourfayaz ◽  
Mahyar Ghazvini ◽  
Omid Mahian ◽  
...  

2017 ◽  
Vol 28 (7) ◽  
pp. 725-743 ◽  
Author(s):  
Anahita Moharamian ◽  
Saeed Soltani ◽  
Faramarz Ranjbar ◽  
Mortaza Yari ◽  
Marc A Rosen

A novel cogeneration system based on a wall mounted gas boiler and an organic Rankine cycle with a hydrogen production unit is proposed and assessed based on energy and exergy analyses. The system is proposed in order to have cogenerational functionality and assessed for the first time. A theoretical research approach is used. The results indicate that the most appropriate organic working fluids for the organic Rankine cycle are HFE700 and isopentane. Utilizing these working fluids increases the energy efficiency of the integrated wall mounted gas boiler and organic Rankine cycle system by about 1% and the organic Rankine cycle net power output about 0.238 kW compared to when the systems are separate. Furthermore, increasing the turbine inlet pressure causes the net power output, the organic Rankine cycle energy and exergy efficiencies, and the cogeneration system exergy efficiency to rise. The organic Rankine cycle turbine inlet pressure has a negligible effect on the organic Rankine cycle mass flow rate. Increasing the pinch point temperature decreases the organic Rankine cycle turbine net output power. Finally, increasing the turbine inlet pressure causes the hydrogen production rate to increase; the highest and lowest hydrogen production rates are observed for the working fluids for HFE7000 and isobutane, respectively. Increasing the pinch point temperature decreases the hydrogen production rate. In the cogeneration system, the highest exergy destruction rate is exhibited by the wall mounted gas boiler, followed by the organic Rankine cycle evaporator, the organic Rankine cycle turbine, the organic Rankine cycle condenser, the proton exchange membrane electrolyzer, and the organic Rankine cycle pump, respectively.


2015 ◽  
Author(s):  
Hongsheng Zhang ◽  
Hongbin Zhao ◽  
Zhenlin Li

A new waste heat recovery scheme based on absorption heat pumps (AHP) applied in CHP (Combined Heat and Power) system was proposed to decrease heating energy consumption of existing CHP systems by recovering waste heat of exhausted steam from a steam turbine of coal-fired direct air cooling units. Based on the establishment of thermodynamic analysis model, through adopting the design parameters of the 135 MW direct air-cooled power plants in China, the performances, especially the exergy losses of the unit as well as its subsystems mainly including six parts at different heating modes were obtained at one specific load. Compared with conventional heating mode, when the thermoelectric ratio is 100%, the power output increases around 3.81 MW, coal consumption rate decreases 11.69 g/(kW·h) and total exergy loss decreases 6.892 MW under 100% THA load, while the energy and exergy efficiencies of the integrated system increase 1.29 % and 1.25 %, respectively. Additionally, the change laws of total exergy loss, energy and exergy efficiency of integrated system at different loads also were studied. The results provide not only theory basis and scientific support for the design of the coal-fired power plants with absorption heat pump recovering waste heat, but also a new scheme of energy saving and optimization for the units.


2020 ◽  
Vol 330 ◽  
pp. 01025
Author(s):  
Larbi Afif ◽  
Nahla Bouaziz

In the context of sustainable development and more particularly the conversion of heat into electricity, the present work proposes a new system of cogeneration operating at low energy value. It’s an organic Rankine cycle, associated with a gas ejector and operating with different organic fluids. It should be noted that the development of the ORC technology is partly a well-adapted response to problems of energy saving and ecosystem preservation. Accordingly, this paper presents a new configuration of a cogeneration system operating at low temperature and ensuring the simultaneous production of electricity and refrigeration. The proposed system is operating under transcritical and subcritical regime using solar energy as thermal source. On the other hand, an energy and exergy study has been developed by choosing the refrigerants R124, R236fa, R1234yf and R1234ze as working fluids according to their low environmental impact and thermodynamic properties. The results of the numerical simulation carried out as part of this study have also shown the importance of integrating the ejector into the proposed machine. Indeed, we investigated the effect of the thermodynamic parameters of the ejector on the coefficient of performance and the exergy efficiency of the cogeneration system.


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