Ideal Point Design and Operation of CO2-Based Transcritical Rankine Cycle (CTRC) System Based on High Utilization of Engine’s Waste Heats

Shi, Lingfeng; Shu, Gequn; Tian, Hua; Huang, Guangdai; Chang, Li-Wen; Chen, Tianyu; Li, Xiaoya

doi:10.3390/en10111692

Cited by 18 publications

(12 citation statements)

References 28 publications

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“…Although the position of the EPOC may vary if other heat pump models of similar technology are considered, the variation should be small, given that the EPOC is determined more by their behaviour against ambient and water inlet temperatures than by their actual performance, and the former derives directly from the cycle topologies and the refrigerants used. The EPOC for larger systems, however, with more complex topologies, such as the ones analysed in [13], or for other applications [28], should be recalculated, as the behaviour of the heat pumps can differ significantly to the ones considered here, affecting the slopes for the COP and w el . It is interesting to study the EPOC more carefully, as shown in Figure 12.…”

Section: Resultsmentioning

confidence: 99%

Comparison of Transcritical CO2 and Conventional Refrigerant Heat Pump Water Heaters for Domestic Applications

et al. 2019

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Although CO 2 as refrigerant is well known for having the lowest global warming potential (GWP), and commercial domestic heat pump water heater systems exist, its long expected wide spread use has not fully unfolded. Indeed, CO 2 poses some technological difficulties with respect to conventional refrigerants, but currently, these difficulties have been largely overcome. Numerous studies show that CO 2 heat pump water heaters can improve the coefficient of performance (COP) of conventional ones in the given conditions. In this study, the performances of transcritical CO 2 and R410A heat pump water heaters were compared for an integrated nearly zero-energy building (NZEB) application. The thermodynamic cycle of two commercial systems were modelled integrating experimental data, and these models were then used to analyse both heat pumps receiving and producing hot water at equal temperatures, operating at the same ambient temperature. Within the range of operation of the system, it is unclear which would achieve the better COP, as it depends critically on the conditions of operation, which in turn depend on the ambient conditions and especially on the actual use of the water. Technology changes on each side of the line of equal performance conditions of operation (EPOC), a useful design tool developed in the study. The transcritical CO 2 is more sensitive to operating conditions, and thus offers greater flexibility to the designer, as it allows improving performance by optimising the global system design.

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Section: Resultsmentioning

confidence: 99%

Comparison of Transcritical CO2 and Conventional Refrigerant Heat Pump Water Heaters for Domestic Applications

et al. 2019

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“…Shi et al [52] conducted theoretical and experimental research on a kW transcritical system. Their aim was to maximize engine waste heat recovery after the integration of a preheater.…”

Section: Transcritical Co 2 Rankine Cyclementioning

confidence: 99%

“…Heat transfer optimization is an important issue in CO 2 transcritical cycles. Shi et al [52] in their research tackled the issue by integrating a preheater in their system. They kept different pumps at fixed speeds and varied the pressure in the gas heater, in the range 7.57-10.35 MPa and obtained a gas heater efficiency of 73-80% and a preheater efficiency of about 90%.…”

Section: Transcritical Co 2 Rankine Cyclementioning

confidence: 99%

Review of Experimental Research on Supercritical and Transcritical Thermodynamic Cycles Designed for Heat Recovery Application

et al. 2019

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Supercritical operation is considered a main technique to achieve higher cycle efficiency in various thermodynamic systems. The present paper is a review of experimental investigations on supercritical operation considering both heat-to-upgraded heat and heat-to-power systems. Experimental works are reported and subsequently analyzed. Main findings can be summarized as: steam Rankine cycles does not show much studies in the literature, transcritical organic Rankine cycles are intensely investigated and few plants are already online, carbon dioxide is considered as a promising fluid for closed Brayton and Rankine cycles but its unique properties call for a new thinking in designing cycle components. Transcritical heat pumps are extensively used in domestic and industrial applications, but supercritical heat pumps with a working fluid other than CO2 are scarce. To increase the adoption rate of supercritical thermodynamic systems further research is needed on the heat transfer behavior and the optimal design of compressors and expanders with special attention to the mechanical integrity.

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“…VALEO's new cooling system reduces engine fuel consumption by an average of 6% [18][19][20][21]. Ehlers in Cummins proposed that a multi-purpose heat exchanger could reduce the mass by 5% and improve the thermal performance [22]. However, few scholars have integrated and optimized the thermal management system as a whole system, failing to integrate waste heat recovery technology, air conditioning systems, engines and coolant systems.…”

Section: Introductionmentioning

confidence: 99%

Analysis and Optimization of Coupled Thermal Management Systems Used in Vehicles

Shu

Tian

et al. 2019

Energies

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About 2/3 of the combustion energy of internal combustion engine (ICE) is lost through the exhaust and cooling systems during its operation. Besides, automobile accessories like the air conditioning system and the radiator fan will bring additional power consumption. To improve the ICE efficiency, this paper designs some coupled thermal management systems with different structures which include the air conditioning subsystem, the waste heat recovery subsystem, engine and coolant subsystem. CO2 is chosen as the working fluid for both the air conditioning subsystem and the waste heat recovery subsystem. After conducting experimental studies and a performance analysis for the subsystems, the coupled thermal management system is evaluated at different environmental temperatures and engine working conditions to choose the best structure. The optimal pump speed increases with the increase of environmental temperature and the decrease of engine load. The optimal coolant utilization rate decreases with the increase of engine load and environmental temperature, and the value is between 38% and 52%. While considering the effect of environmental temperature and road conditions of real driving and the energy consumption of all accessories of the thermal management system, the optimal thermal management system provides a net power of 4.2 kW, improving the ICE fuel economy by 1.2%.

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Ideal Point Design and Operation of CO2-Based Transcritical Rankine Cycle (CTRC) System Based on High Utilization of Engine’s Waste Heats

Cited by 18 publications

References 28 publications

Comparison of Transcritical CO2 and Conventional Refrigerant Heat Pump Water Heaters for Domestic Applications

Comparison of Transcritical CO2 and Conventional Refrigerant Heat Pump Water Heaters for Domestic Applications

Review of Experimental Research on Supercritical and Transcritical Thermodynamic Cycles Designed for Heat Recovery Application

Analysis and Optimization of Coupled Thermal Management Systems Used in Vehicles

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