scholarly journals Development of advanced low-temperature heat transfer fluids for district heating and cooling

1991 ◽  
Author(s):  
Keyword(s):  
Heat Transfer ◽  
Low Temperature ◽  
District Heating ◽  
Heat Transfer Fluids ◽  
Heating And Cooling ◽  
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 Low Temperature District Heating: An Expert Opinion Survey

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 810 ◽  
Author(s):  
Alessandro Guzzini ◽  
Marco Pellegrini ◽  
Edoardo Pelliconi ◽  
Cesare Saccani
Keyword(s):  
Low Temperature ◽  
System Development ◽  
Renewable Energy Sources ◽  
District Heating ◽  
Pollutant Emissions ◽  
Heating And Cooling ◽  
Depth Analysis ◽  
Smart Energy Systems ◽  
International Experts ◽  
Expert Opinion Survey

Among the available solutions for building heating and cooling, district heating (DH) and district cooling (DC) systems are considered some of the best options since they can ensure a better control of pollutant emissions and greater efficiency than individual systems. Nevertheless, improvements are needed to increase their sustainability and reliability. The so-called “low temperature district heating” (LTDH) concept has been introduced in recent years in an attempt (i) to reduce the distribution heat losses through a temperature decrease in the DH network, (ii) to favor the integration with renewable energy sources, and (iii) to create the conditions required for the development of future smart energy systems. However, many concerns have been raised about its implementation in both existing and new systems. For this reason, this paper aims to identify the stakeholders’ ranking of the barriers against LTDH system development and implementation over the next few years. Aiming to this, a questionnaire was designed, including an analysis of current gaps and strengths, and then submitted to more than 50 Italian and international experts in the field of DH. An in-depth analysis of the received answers was performed, focusing in particular on the Italian experts’ answers. Comments and suggestions on how to promote the transition to the new LTDH approach are reported.

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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