Heat Transfer in the Heating Zone of Low-Temperature Heat Pipes

AIAA Journal ◽  
1979 ◽  
Vol 17 (12) ◽  
pp. 1390-1394 ◽  
Author(s):  
V. I. Tolubinsky ◽  
V. A. Antonenko ◽  
Yu. N. Ostrovsky ◽  
E.N. Shevchuk
Keyword(s):  
Heat Transfer ◽  
Low Temperature ◽  
Heat Pipes ◽  
Heating Zone ◽  
Temperature Heat

scholarly journals Analysis and Comparison of Some Low-Temperature Heat Sources for Heat Pumps

Energies ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1853 ◽  
Author(s):  
Pavel Neuberger ◽  
Radomír Adamovský
Keyword(s):  
Heat Transfer ◽  
Low Temperature ◽  
Heat Source ◽  
Heat Pump ◽  
Heat Exchangers ◽  
Ambient Air ◽  
Heat Transfer Fluid ◽  
Heat Sources ◽  
Ground Heat Exchangers ◽  
Temperature Heat

The efficiency of a heat pump energy system is significantly influenced by its low-temperature heat source. This paper presents the results of operational monitoring, analysis and comparison of heat transfer fluid temperatures, outputs and extracted energies at the most widely used low temperature heat sources within 218 days of a heating period. The monitoring involved horizontal ground heat exchangers (HGHEs) of linear and Slinky type, vertical ground heat exchangers (VGHEs) with single and double U-tube exchanger as well as the ambient air. The results of the verification indicated that it was not possible to specify clearly the most advantageous low-temperature heat source that meets the requirements of the efficiency of the heat pump operation. The highest average heat transfer fluid temperatures were achieved at linear HGHE (8.13 ± 4.50 °C) and double U-tube VGHE (8.13 ± 3.12 °C). The highest average specific heat output 59.97 ± 41.80 W/m2 and specific energy extracted from the ground mass 2723.40 ± 1785.58 kJ/m2·day were recorded at single U-tube VGHE. The lowest thermal resistance value of 0.07 K·m2/W, specifying the efficiency of the heat transfer process between the ground mass and the heat transfer fluid, was monitored at linear HGHE. The use of ambient air as a low-temperature heat pump source was considered to be the least advantageous in terms of its temperature parameters.

Emitting radiator based on low-temperature heat pipes

1995 ◽  
Vol 67 (1-2) ◽  
pp. 764-768
Author(s):  
L. L. Vasil'ev ◽  
L. E. Kanonchik
Keyword(s):  
Low Temperature ◽  
Heat Pipes ◽  
Temperature Heat

Suppression of the Sonic Heat Transfer Limit in High-Temperature Heat Pipes

1989 ◽  
Vol 111 (3) ◽  
pp. 605-610 ◽  
Author(s):  
Flavio Dobran
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Heat Pipes ◽  
Vapor Flow ◽  
Transport Capacity ◽  
Flow Area ◽  
Temperature Heat ◽  
Liquid Evaporation ◽  
Heat Transfer Limit ◽  
Axial Heat

The design of high-performance heat pipes requires optimization of heat transfer surfaces and liquid and vapor flow channels to suppress the heat transfer operating limits. In the paper an analytical model of the vapor flow in high-temperature heat pipes is presented, showing that the axial heat transport capacity limited by the sonic heat transfer limit depends on the working fluid, vapor flow area, manner of liquid evaporation into the vapor core of the evaporator, and lengths of the evaporator and adiabatic regions. Limited comparisons of the model predictions with data of the sonic heat transfer limits are shown to be very reasonable, giving credibility to the proposed analytical approach to determine the effect of various parameters on the axial heat transport capacity. Large axial heat transfer rates can be achieved with large vapor flow cross-sectional areas, small lengths of evaporator and adiabatic regions or a vapor flow area increase in these regions, and liquid evaporation in the evaporator normal to the main flow.

scholarly journals Use of Low-Temperature Heat Transfer Agents in the Work of Heat Pumps in Sub-zero Temperatures Conditions

2019 ◽  
Vol 157 ◽  
pp. 1456-1461
Author(s):  
Alexey N. Vasiliev ◽  
Olga V. Shepovalova ◽  
Evgenia V. Tutunina
Keyword(s):  
Heat Transfer ◽  
Low Temperature ◽  
Heat Pumps ◽  
Temperature Heat ◽  
Transfer Agents
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