Study on Cooling Heat Transfer of Supercritical Carbon Dioxide Applied to Transcritical Carbon Dioxide Heat Pump

2021 ◽  
pp. 451-493
Author(s):  
Chaobin Dang ◽  
Eiji Hihara
Keyword(s):  
Heat Transfer ◽  
Carbon Dioxide ◽  
Heat Pump ◽  
Supercritical Co2 ◽  
Lubricating Oil ◽  
Cross Sectional ◽  
Pump System ◽  
Heat Pump System ◽  
Transcritical Carbon Dioxide ◽  
Supercritical Water Cooled Reactor

Understanding the heat transfer characteristics of supercritical fluids is of fundamental importance in many industrial processes such as transcritical heat pump system, supercritical water-cooled reactor, supercritical separation, and supercritical extraction processes. This chapter addresses recent experimental, theoretical, and numerical studies on cooling heat transfer of supercritical CO2. A systematic study on heat transfer coefficient and pressure drop of supercritical CO2 was carried out at wide ranges of tube diameter, mass flux, heat flux, temperature, and pressure. Based on the understanding of temperature and velocity distributions at cross-sectional direction provided by the numerical simulation, a new prediction model was proposed, which agreed well with the experimental results. In addition, the effect of lubricating oil was also discussed with the focus on the change in flow pattern and heat transfer performance of oil and supercritical CO2.

Study on Cooling Heat Transfer of Supercritical Carbon Dioxide Applied to Transcritical Carbon Dioxide Heat Pump

2017 ◽  
pp. 292-334
Author(s):  
Chaobin Dang ◽  
Eiji Hihara
Keyword(s):  
Heat Transfer ◽  
Carbon Dioxide ◽  
Heat Pump ◽  
Supercritical Co2 ◽  
Lubricating Oil ◽  
Cross Sectional ◽  
Pump System ◽  
Heat Pump System ◽  
Transcritical Carbon Dioxide ◽  
Supercritical Water Cooled Reactor

Understanding the heat transfer characteristics of supercritical fluids is of fundamental importance in many industrial processes such as transcritical heat pump system, supercritical water-cooled reactor, supercritical separation and supercritical extraction processes. This paper addresses recent experimental, theoretical and numerical studies on cooling heat transfer of supercritical CO2. A systematic study on heat transfer coefficient and pressure drop of supercritical CO2 was carried out at wide ranges of tube diameter, mass flux, heat flux, temperature and pressure. Based on the understanding of temperature and velocity distributions at cross-sectional direction provided by the numerical simulation, a new prediction model was proposed, which agreed well with the experimental results. In addition, the effect of lubricating oil was also discussed with the focus on the change in flow pattern and heat transfer performance of oil and supercritical CO2.

The Experimental Investigation and Theoretical Analysis on Transcritical Carbon Dioxide Heat Pump Cycle

2012 ◽  
Vol 455-456 ◽  
pp. 240-245
Author(s):  
Lu Xiang Zong ◽  
Jian Lin Liu ◽  
Xue Shi ◽  
Ying Bai Xie
Keyword(s):  
Carbon Dioxide ◽  
Experimental Investigation ◽  
Theoretical Analysis ◽  
Heat Pump ◽  
Coefficient Of Performance ◽  
Pump System ◽  
Working Fluids ◽  
Heat Pump System ◽  
Exit Temperature ◽  
Transcritical Carbon Dioxide

The (H)CFC-phase out and the fear for future problems for other synthetic working fluids, because of their known and unknown impact on the environment, have introduced a rising interest in environmentally safe natural working fluids. CO2is one of the few non-toxic and non-flammable working fluids that do not contribute to ozone depletion or global warming, if leaked to the atmosphere. Because the critical temperature of CO2is only 31.1°C, the transcritical cycle can be used to improve the coefficient of performance of the system. The experimental investigation and theoretical analysis on transcritical carbon dioxide heat pump system are carried out in this paper. It points out that there is an optimum operational pressure on transcritical carbon dioxide heat pump cycle, when the outlet temperature of gas cooler is constant, the coefficient of performance increases with increasing evaporating temperature at the same conditions, and the operational efficiency increased with decrease of gas cooler exit temperature. So in order to obtain the optimum performance, the influence of evaporating temperature, gas cooler exit temperature, and the operational pressure should be considered during the designing and operating transcritical carbon dioxide heat pump system.

The Thermodynamic Analysis and Experimental Investigation on Transcritical Carbon Dioxide Heat Pump System

2010 ◽  
Author(s):  
Yingbai Xie ◽  
Yingfu Liu ◽  
Yingcheng Mai ◽  
Luxiang Zong
Keyword(s):  
Carbon Dioxide ◽  
Experimental Investigation ◽  
Heat Pump ◽  
Thermodynamic Analysis ◽  
Coefficient Of Performance ◽  
Pump System ◽  
Heat Pump System ◽  
Exit Temperature ◽  
Transcritical Carbon Dioxide ◽  
Critical Carbon Dioxide

Synthetic refrigerants such as CFCs and HCFCs deplete ozone and cause greenhouse effect. CO2 as a natural working fluid has zero Ozone Depletion Potential and its Global Warming Potential is equal to 1, is receiving more and more attention in the refrigeration field. Because the critical temperature of CO2 is only 31.1°c, the trans-critical cycle can be used to improve the coefficient of performance of the system. The thermodynamic analysis and experimental investigation on trans-critical carbon dioxide heat pump system are carried out in this paper. It points out that there is an optimum operational pressure on trans-critical carbon dioxide heat pump cycle, when the outlet temperature of gas cooler is constant, the coefficient of performance increases with increasing evaporating temperature at the same conditions, and the operational efficiency increased with decrease of gas cooler exit temperature. So in order to obtain the optimum performance, the influence of evaporating temperature, gas cooler exit temperature, and the operational pressure should be considered during the designing and operating transcritical carbon dioxide heat pump system.

scholarly journals Performance and Exergy Transfer Analysis of Heat Exchangers with Graphene Nanofluids in Seawater Source Marine Heat Pump System

Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1762 ◽  
Author(s):  
Zhe Wang ◽  
Fenghui Han ◽  
Yulong Ji ◽  
Wenhua Li
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Pump ◽  
Heat Exchangers ◽  
Transfer Model ◽  
Enhanced Heat Transfer ◽  
Pump System ◽  
Heat Pump System ◽  
Tube Heat Exchanger ◽  
Exergy Transfer

A marine seawater source heat pump is based on the relatively stable temperature of seawater, and uses it as the system’s cold and heat source to provide the ship with the necessary cold and heat energy. This technology is one of the important solutions to reduce ship energy consumption. Therefore, in this paper, the heat exchanger in the CO2 heat pump system with graphene nano-fluid refrigerant is experimentally studied, and the influence of related factors on its heat transfer enhancement performance is analyzed. First, the paper describes the transformation of the heat pump system experimental bench, the preparation of six different mass concentrations (0~1 wt.%) of graphene nanofluid and its thermophysical properties. Secondly, this paper defines graphene nanofluids as beneficiary fluids, the heat exchanger gains cold fluid heat exergy increase, and the consumption of hot fluid heat is heat exergy decrease. Based on the heat transfer efficiency and exergy efficiency of the heat exchanger, an exergy transfer model was established for a seawater source of tube heat exchanger. Finally, the article carried out a test of enhanced heat transfer of heat exchangers with different concentrations of graphene nanofluid refrigerants under simulated seawater constant temperature conditions and analyzed the test results using energy and an exergy transfer model. The results show that the enhanced heat transfer effect brought by the low concentration (0~0.1 wt.%) of graphene nanofluid is greater than the effect of its viscosity on the performance and has a good exergy transfer effectiveness. When the concentration of graphene nanofluid is too high, the resistance caused by the increase in viscosity will exceed the enhanced heat transfer gain brought by the nanofluid, which results in a significant decrease in the exergy transfer effectiveness.

Characteristics Study of Sewage Source Heat Pump System Based on Heat Transfer Enhancement and Acoustic Cavitation Decontamination

2014 ◽  
Vol 665 ◽  
pp. 607-610
Author(s):  
Jian Feng Qian ◽  
Ya Yuan Liu
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Heat Pump ◽  
Treatment Time ◽  
Acoustic Cavitation ◽  
Ultrasonic Cavitation ◽  
Transfer Enhancement ◽  
Pump System ◽  
Heat Pump System ◽  
Sewage Source

Put forward an application of ultrasonic cavitation technology of the sewage source heat pump system to solve the problem of controlling pollution and emphatically discusses the principle of acoustic cavitation and the effect, to conduct a feasibility analysis of Anti-fouling in sewage source heat pump sewage side. Through analysis principle of ultrasonic cavitation and heat transfer enhancement for carrying the experiment, study the pattern of scaling in heat exchange tube for different velocity and viscosity, effect in flow rate on the ultrasonic cleaning wastewater, Effect in ultrasonic treatment time on the descaling result. Obtain that it can enhancement transfer for 48%.

Determination of Heat Transfer Characteristics of Solar Thermal Collectors as Heat Source for a Residential Heat Pump

2016 ◽  
Vol 138 (4) ◽  
Author(s):  
Maarten G. Sourbron ◽  
Nesrin Ozalp
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Low Temperature ◽  
Heat Source ◽  
Heat Pump ◽  
Solar Collector ◽  
Heat Transfer Characteristics ◽  
Pump System ◽  
Heat Pump System ◽  
Temperature Heat

With reducing energy demand and required installed mechanical system power of modern residences, alternate heat pump system configurations with a possible increased economic viability emerge. Against this background, this paper presents a numerically examined energy feasibility study of a solar driven heat pump system for a low energy residence in a moderate climate, where a covered flat plate solar collector served as the sole low temperature heat source. A parametric study on the ambient-to-solarfluid heat transfer coefficient was conducted to determine the required solar collector heat transfer characteristics in this system setup. Moreover, solar collector area and storage tank volume were varied to investigate their impact on the system performance. A new performance indicator “availability” was defined to assess the contribution of the solar collector as low temperature energy source of the heat pump. Results showed that the use of a solar collector as low temperature heat source was feasible if its heat transfer rate (UA-value) was 200 W/K or higher. Achieving this value with a realistic solar collector area (A-value) required an increase of the overall ambient-to-solarfluid heat transfer coefficient (U-value) with a factor 6–8 compared to the base case with heat exchange between covered solar collector and ambient.

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