Experimental and theory investigations on falling film flow characteristics and heat extraction performance of spray heat exchanger for sewage heat pump system

A ground source heat pump system is a high-performance technology used for maintaining a stable underground temperature all year-round. However, the high costs for installation, such as for boring and drilling, is a drawback that prevents the system to be rapidly introduced into the market. This study proposes a modular ground heat exchanger (GHX) that can compensate for the disadvantages (such as high-boring/drilling costs) of the conventional vertical GHX. Through a real-scale experiment, a modular GHX was manufactured and buried at a depth of 4 m below ground level; the heat exchange rate and the change in underground temperatures during the GHX operation were tracked and calculated. The average heat exchanges rate was 78.98 W/m and 88.83 W/m during heating and cooling periods, respectively; the underground temperature decreased by 1.2 °C during heat extraction and increased by 4.4 °C during heat emission, with the heat pump (HP) working. The study showed that the modular GHX is a cost-effective alternative to the vertical GHX; further research is needed for application to actual small buildings.

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D106 Heat Transfer and Flow Characteristics of Heat Exchanger for Heat Pump System Using Carbon Dioxide as a Working Fluid

Proceedings of thermal engineering conference ◽

10.1299/jsmeptec.2001.0_151 ◽

2001 ◽

Vol 2001 (0) ◽

pp. 151-152

Author(s):

Tomohiro HONDA ◽

Lei GAO

Keyword(s):

Heat Transfer ◽

Carbon Dioxide ◽

Heat Exchanger ◽

Heat Pump ◽

Flow Characteristics ◽

Working Fluid ◽

Pump System ◽

Heat Pump System

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Theoretical and Experimental Study on the Falling-Film Evaporator Applied to Mechanical Vapor Compression

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.753-755.2667 ◽

2013 ◽

Vol 753-755 ◽

pp. 2667-2673 ◽

Cited By ~ 1

Author(s):

Wei Ke Pang ◽

Lu Wei Yang ◽

Zhen Tao Zhang

Keyword(s):

Heat Transfer ◽

Heat Pump ◽

High Efficiency ◽

Film Flow ◽

Falling Film ◽

Vapor Compression ◽

Pump System ◽

Heat Pump System ◽

Film Evaporator ◽

Heat Transfer Efficiency

Based on a heat pump system of mechanical vapor recompression (MVR) designed and manufactured independently, the heat transfer performance of falling-film evaporator was measured by a combination way of theory analysis and experiment proving as the heat pump operated in practice. After the result of theoretical calculation is worked out, the start thickness and entrance velocity of the liquid film are established by adjusting the flux of raw solution. The result shows there is an optimization that the film thickness at the bottom of the tubes amounts to that of boundary layer of velocity. Additionally, it is a process of falling-film flow with heat and mass transfer between the start and end of falling-film. The last thickness of the falling film is about 0.21~0.44mm. The thickness of falling film when the falling-film flowed and heat exchange was over is compared with each other, and the effect of heat resistance on heat transfer is discussed also. It is showed that an optimal thickness is formed during the process of falling-film flow and evaporation, and disadvantages come up when it is not formed. The falling-film evaporator propelled by the MVR heat pump with low compression ratio carries through a process of strong and high-efficiency heat transfer with phase transition. It is because the states of produced vapor both before compressed and after compressed are saturated. Its heat-transfer coefficient may be as high as 1990 W/ (m2·K). The start and end thickness of falling film become great while the evaporation pressure goes up. It leads to the drop of the heat-transfer efficiency, so there is an optimization to the system in all probability.

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The Solar-Assisted Vertical Ground Source Heat Pump System in Cold Climates—A Case Study

Proceedings ◽

10.3390/proceedings2020051024 ◽

2020 ◽

Vol 51 (1) ◽

pp. 24

Author(s):

Piotr Rynkowski

Keyword(s):

Heat Exchanger ◽

Heat Pump ◽

Solar Collector ◽

Heat Extraction ◽

Ground Heat Exchanger ◽

Ground Source Heat Pump ◽

Pump System ◽

Heat Pump System ◽

Ground Source ◽

Vertical Ground

In this paper, experimental studies were performed for a solar ground source heat pump system (SGSHPS) with a vertical ground heat exchanger (VGHE). The experiment was operated during the summer in 2018. The heat from the solar collector was monitored by measuring the inlet and outlet temperatures and flow rate of the heat transfer fluids. An energy equilibrium balance carried out indicates heat extraction from the solar collector to the ground heat exchanger. It has been established that clear impact is achieved within a radius of 5 m. The average temperature of the actively regenerated borehole was higher than that of the undisturbed profile, which has a direct impact on the significant benefits of the coefficient of performance (COP) of the ground source heat pump system (GSHPS) and effectively helps soil regeneration. The average efficiency ratio of the heat transferred from solar radiation to soil in the SGSHPS was 42.3%.

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