Low-Temperature Drying Using a Versatile Heat Pump Dehumidifier

2003 ◽  
Vol 21 (3) ◽  
pp. 539-554 ◽  
Author(s):  
V. Sosle ◽  
G. S. V. Raghavan ◽  
R. Kittler
Keyword(s):  
Low Temperature ◽  
Heat Pump ◽  
Low Temperature Drying

scholarly journals Heat pump technologies of low temperature drying of capillary-porous materials spherical shape

2020 ◽  
pp. 7-12
Author(s):  
Yu.F. Snezhkin ◽  
V.М. Paziuk ◽  
Zh.O. Petrova
Keyword(s):  
Low Temperature ◽  
Porous Materials ◽  
Heat Pump ◽  
Experimental Studies ◽  
Average Energy ◽  
Spherical Shape ◽  
High Energy ◽  
Heat Pumps ◽  
Heat Pump Drying ◽  
Low Temperature Drying

Heat pump technologies have become widely used in space heating and air conditioning systems, and the heat pump can be used for low-temperature drying of capillary-porous materials. Recuperative and condensing heat pumps, which allow both drying and cooling of the material, have become the most widespread. The developed condensing heat pump drying unit with a mine chamber implements a low-temperature drying process of spherical capillary-porous materials at a drying agent temperature of 40-50°C with a decrease in material humidity by 11% to a final humidity of 8%. Experimental studies on a heat pump drying unit for drying capillary-porous materials of spherical shape indicated a significant reduction in average energy costs per process up to 3700 - 4100 kJ/kg of evaporated moisture. The increase in energy consumption increases significantly in the second part of the second period, where heat consumption can reach 5000 - 5350 kJ/kg of evaporated moisture. The use of condensing heat pumps for low-temperature drying of capillary-porous materials has shown high energy efficiency compared to existing drying technologies.

scholarly journals Local Heating Networks with Waste Heat Utilization: Low or Medium Temperature Supply?

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 954 ◽  
Author(s):  
Hanne Kauko ◽  
Daniel Rohde ◽  
Armin Hafner
Keyword(s):  
Low Temperature ◽  
Heat Pump ◽  
Urban Areas ◽  
Waste Heat ◽  
Local Heating ◽  
District Heating ◽  
Heat Pumps ◽  
Hot Water ◽  
Local Network ◽  
Medium Temperature

District heating enables an economical use of energy sources that would otherwise be wasted to cover the heating demands of buildings in urban areas. For efficient utilization of local waste heat and renewable heat sources, low distribution temperatures are of crucial importance. This study evaluates a local heating network being planned for a new building area in Trondheim, Norway, with waste heat available from a nearby ice skating rink. Two alternative supply temperature levels have been evaluated with dynamic simulations: low temperature (40 °C), with direct utilization of waste heat and decentralized domestic hot water (DHW) production using heat pumps; and medium temperature (70 °C), applying a centralized heat pump to lift the temperature of the waste heat. The local network will be connected to the primary district heating network to cover the remaining heat demand. The simulation results show that with a medium temperature supply, the peak power demand is up to three times higher than with a low temperature supply. This results from the fact that the centralized heat pump lifts the temperature for the entire network, including space and DHW heating demands. With a low temperature supply, heat pumps are applied only for DHW production, which enables a low and even electricity demand. On the other hand, with a low temperature supply, the district heating demand is high in the wintertime, in particular if the waste heat temperature is low. The choice of a suitable supply temperature level for a local heating network is hence strongly dependent on the temperature of the available waste heat, but also on the costs and emissions related to the production of district heating and electricity in the different seasons.

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.

Potential for Aflatoxin Development in Low Temperature Drying Systems

1979 ◽  
Vol 22 (6) ◽  
pp. 1439-1443 ◽  
Author(s):  
I. J. Ross ◽  
O. J. Loewer ◽  
G. M. White
Keyword(s):  
Low Temperature ◽  
Low Temperature Drying

Heat Pump Efficiency in fifth Generation Ultra-Low Temperature District Heating Networks using a Wastewater Heat Source

Energy ◽  
2021 ◽  
pp. 121318
Author(s):  
Tobias Reiners ◽  
Michel Gross ◽  
Lisa Altieri ◽  
Hermann-Josef Wagner ◽  
Valentin Bertsch
Keyword(s):  
Low Temperature ◽  
Heat Source ◽  
Heat Pump ◽  
District Heating ◽  
Pump Efficiency ◽  
Fifth Generation ◽  
Heating Networks
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