Research on the Region Division for Supercritical CO2 Cooling Heat Transfer in Gas Cooler

2014 ◽  
Vol 1008-1009 ◽  
pp. 1084-1087
Author(s):  
Ying Bai Xie ◽  
Yi Chen ◽  
Ti Jun Wang
Keyword(s):  
Heat Transfer ◽  
Supercritical Co2 ◽  
Heat Transfer Characteristic ◽  
Transfer Characteristic ◽  
Correlation Equations ◽  
Pump System ◽  
Heat Pump System ◽  
Supercritical Region ◽  
Region Division ◽  
Well Design

In gas cooler, a key component of transcritical heat pump system, CO2 is always in supercritical status. A well design gas cooler should get the full informations of supercritcal CO2 in-tube cooling heat transfer characteristic. An EES program is developed to calculate the supercritical CO2 cooling heat transfer performances based on 4 selected correlation equations. According to the results and the thermopgysical parameters of supercritical CO2, such as specific heat, density, thermal conductivity and dynamic viscosity, two region, the starting area of supercritical region and the main supercritical region, is suggested for supercritical CO2 cooling heat transfer by temperature at 80°C. In the staring area, the variations of heat transfer and other parameters are intensive, while in the main supercritical region, the variations are clined to be stable.

The Influence of Soil Heat Imbalance on Ground-Coupled Heat Pump System and Strategy

2010 ◽  
Author(s):  
Rui Fan ◽  
Yan Gao ◽  
Yingqian Song ◽  
Weiding Long
Keyword(s):  
Heat Transfer ◽  
Heat Pump ◽  
Heat Transfer Characteristic ◽  
Transfer Characteristic ◽  
Pump System ◽  
Efficient Operation ◽  
Heat Pump System ◽  
Adjustment Strategy ◽  
Ground Coupled Heat Pump ◽  
Heat Requirement

It is well noticed that imbalance between winter heat requirement and summer heat gain in soil has an effect on heat transfer characteristic of ground heat exchanger (GHE), which results into the decrease of operation efficiency of ground-coupled heat pump system year by year. Therefore, the research on heat transfer characteristic of GHE for different heat imbalance rate is firstly presented in the article, and then, based on numerical model of heating conduction and groundwater heat advection, the influence of groundwater flow rate is analyzed. Finally, several suggestions such as auxiliary cool and heat source, GHE adjustment strategy are put forward for better and efficient operation of system.

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.

scholarly journals Effect of the Pumping-injection flow rate on Heat Transfer Characteristic of Borehole Heat Exchangers for Coupling Ground-Source Heat Pump System

2020 ◽  
Author(s):  
Jiuchen Ma ◽  
Qian Jiang ◽  
Qiuli Zhang ◽  
Yacheng Xie ◽  
Yahui Wang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Flow Rate ◽  
Heat Exchangers ◽  
Transfer Characteristic ◽  
Ground Source Heat Pump ◽  
Pump System ◽  
Heat Pump System ◽  
Injection Flow Rate ◽  
Injection Flow ◽  
Ground Source

Abstract A coupling ground source heat pump system (CGSHP) is established in areas where groundwater is shallow but the seepage velocity is weak, which sets up pumping and injection wells on both sides of borehole heat exchangers (BHEs). A convection-dispersion analytical model of excess temperature in aquifer that considers groundwater forced seepage and axial effects and thermal dispersion effects is proposed. A controllable forced seepage sandbox is built by equation analysis method and similarity criteria. Through indoor test and the proposed analytical model, the correctness and accuracy of the numerical simulation software FEFLOW7.1 is verified. The influence of different pumping-injection flow rate on the heat transfer characteristic of BHEs is studied by numerical simulation. The results show that the average heat efficiency coefficient of BHEs increases and the heat influence range of downstream BHEs expands with the increasing of pumping-injection flow rate. The relation curve between Pe and the increment of heat transfer rate per unit depth of BHEs (Δ`q) is distributed as Gaussian function. The pumping-injection flow rate that makes Darcy velocity reaches 0.6×10-6~1.4×10-6 m∙s-1 in the aquifer is the best reference range for CGSHP system，so 400~600 m3∙d-1 is taken as the best pumping-injection flow rate in this paper.

scholarly journals Effect of the Pumping-injection flow rate on Heat Transfer Characteristic of Borehole Heat Exchangers for Coupling Ground-Source Heat Pump System

2020 ◽  
Author(s):  
Jiuchen Ma ◽  
Qian Jiang ◽  
QuLi Zhang ◽  
Yacheng Xie ◽  
Yahui Wang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Flow Rate ◽  
Heat Exchangers ◽  
Transfer Characteristic ◽  
Ground Source Heat Pump ◽  
Pump System ◽  
Heat Pump System ◽  
Injection Flow Rate ◽  
Injection Flow ◽  
Ground Source

Abstract A coupling ground source heat pump system (CGSHP) is established in areas where groundwater is shallow but the seepage velocity is weak, which sets up pumping and injection wells on both sides of borehole heat exchangers (BHEs). A convection-dispersion analytical model of excess temperature in aquifer that considers groundwater forced seepage and axial effects and thermal dispersion effects is proposed. A controllable forced seepage sandbox is built by equation analysis method and similarity criteria. Through indoor test and the proposed analytical model, the correctness and accuracy of the numerical simulation software FEFLOW7.1 is verified. The influence of different pumping-injection flow rate on the heat transfer characteristic of BHEs is studied by numerical simulation. The results show that the average heat efficiency coefficient of BHEs increases and the heat influence range of downstream BHEs expands with the increasing of pumping-injection flow rate. The relation curve between Pe and the increment of heat transfer rate per unit depth of BHEs (Δ`q) is distributed as Gaussian function. The pumping-injection flow rate that makes Darcy velocity reaches 0.6 × 10− 6~1.4 × 10− 6 m∙s− 1 in the aquifer is the best reference range for CGSHP system,so 400 ~ 600 m3∙d− 1 is taken as the best pumping-injection flow rate in this paper.

scholarly journals Effect of the Pumping-injection flow rate on Heat Transfer Characteristic of Borehole Heat Exchangers for Coupling Ground-Source Heat Pump System

2020 ◽  
Author(s):  
Jiuchen Ma ◽  
Qian Jiang ◽  
Qiuli Zhang ◽  
Yacheng Xie ◽  
Yahui Wang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Flow Rate ◽  
Heat Exchangers ◽  
Transfer Characteristic ◽  
Ground Source Heat Pump ◽  
Pump System ◽  
Heat Pump System ◽  
Injection Flow Rate ◽  
Injection Flow ◽  
Ground Source

Abstract A coupling ground source heat pump system (CGSHP) is established in areas where groundwater is shallow but the seepage velocity is weak, which sets up pumping and injection wells on both sides of borehole heat exchangers (BHEs). A convection-dispersion analytical model of excess temperature in aquifer that considers groundwater forced seepage and axial effects and thermal dispersion effects is proposed. A controllable forced seepage sandbox is built by equation analysis method and similarity criteria. Through indoor test and the proposed analytical model, the correctness and accuracy of the numerical simulation software FEFLOW7.1 is verified. The influence of different pumping-injection flow rate on the heat transfer characteristic of BHEs is studied by numerical simulation. The results show that the average heat efficiency coefficient of BHEs increases and the heat influence range of downstream BHEs expands with the increasing of pumping-injection flow rate. The relation curve between Pe and the increment of heat transfer rate per unit depth of BHEs (Δ‾ q ) is distributed as Gaussian function. The pumping-injection flow rate that makes Darcy velocity reaches 0.6×10 -6 ~1.4×10 -6 m∙s -1 in the aquifer is the best reference range for CGSHP system,so 400~600 m 3 ∙d -1 is taken as the best pumping-injection flow rate in this paper.

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.

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