A Technique for Attaching Fine Wires to Provide a Large Surface Area for Low Temperature Heat Transfer

1971 ◽  
Vol 42 (7) ◽  
pp. 1087-1089
Author(s):  
W. P. Kirk ◽  
S. H. Castles ◽  
E. D. Adams
Keyword(s):  
Heat Transfer ◽  
Low Temperature ◽  
Surface Area ◽  
Large Surface Area ◽  
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.

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

Low-temperature synthesis of δ-MnO2 with large surface area and its capacitance

2010 ◽  
Vol 64 (16) ◽  
pp. 1763-1765 ◽  
Author(s):  
Gang Zhu ◽  
Hongjuan Li ◽  
Lingjuan Deng ◽  
Zong-Huai Liu
Keyword(s):  
Low Temperature ◽  
Surface Area ◽  
Large Surface Area ◽  
Low Temperature Synthesis ◽  
Temperature Synthesis

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.

The Interaction Effect Study of Ash Deposition and Acid Condensation on Low-Temperature Heat Transfer Surface in Boiler Flue Gas

2017 ◽  
Author(s):  
Lei Ma ◽  
Fengzhong Sun ◽  
Wei Wei ◽  
Jiayou Liu ◽  
Yuetao Shi
Keyword(s):  
Heat Transfer ◽  
Low Temperature ◽  
Flue Gas ◽  
Influence Factors ◽  
Outer Wall ◽  
Heat Transfer Surface ◽  
Ash Deposition ◽  
Temperature Heat ◽  
Flue Temperature ◽  
Double Pipe

The ash deposition on low-temperature heat transfer surface is a key factor that deteriorates the heat transfer performance and leads to corrosion in the low pressure economizer. In the low temperature flue gas, ash deposition is closely related with acid condensation. The sulfuric acid vapor and water vapor contained in the flue gas will condense on heat transfer surface under low flue temperature, which will aggravate ash deposition. In order to evaluate the influence factors of ash deposition on low-temperature heat transfer surface, a laboratory experiment is carried out in this paper. The acid concentration of flue gas, the ash content, the ash component, the flue temperature and the temperature of heat transfer surface are considered to be the most important influence factors on ash deposition characteristics. The viscosity of ash deposition samples on the outer wall of the double-pipe is measured to describe ash deposition characteristics. The fouling factor is calculated. Meanwhile, the scanning electron microscope SEM is used to the analysis of ash samples obtained from the outer wall of the double-pipe. As conclusion, the changing regulation of viscosity of ash deposition on low-temperature heat transfer surface is obtained. (CSPE)

Sign in / Sign up

Export Citation Format

Share Document