Performance Analysis of a Cascading Adsorption Cycle Powered by High-Temperature Heat Sources for Low-Temperature Cooling in Hot Climates

2020 ◽  
Vol 12 (5) ◽  
Author(s):  
Dalila Abbaz ◽  
Abla Chaker ◽  
Mahmoud Bourouis
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Low Temperatures ◽  
Thermal Conditions ◽  
Coefficient Of Performance ◽  
Large Temperature ◽  
Heat Sources ◽  
Adsorption Refrigeration ◽  
Temperature Heat ◽  
Adsorption Cycle

Abstract Cascade adsorption refrigeration technology using high-temperature driving heat is a very promising option for low-temperature cooling applications due to the large temperature difference between the heat source and the cold distributed. The present work carried out a feasibility and parametric study in order to analyze the functioning of a cascading adsorption cycle using the working pair zeolite/ammonia in beds operating at high temperatures and activated carbon/ammonia in those operating at low temperatures. At the nominal thermal conditions, namely, heating, condensing, and evaporating temperatures of 280 °C, 35 °C, and (−5) °C, respectively, the coefficient of performance (COP) and the specific refrigerating capacity (SCP) of the cycle were 0.53 and 67.1 W/kg. When the driving temperature is varied from 260 °C to 320 °C, the COP increases by 57% and the SCP by 36%. The performance of the cascading adsorption cycle at negative evaporating temperatures is very satisfactory.

Thermodynamic peculiarities of alpha-type Stirling engines for low-temperature difference power generation: Optimisation of operating parameters and heat exchangers using a third-order model

2013 ◽  
Vol 228 (11) ◽  
pp. 1936-1947 ◽  
Author(s):  
Benedikt Hoegel ◽  
Dirk Pons ◽  
Michael Gschwendtner ◽  
Alan Tucker ◽  
Mathieu Sellier
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Temperature Difference ◽  
Heat Exchangers ◽  
Operating Parameters ◽  
Heat Sources ◽  
Third Order ◽  
Concentrated Solar Energy ◽  
Stirling Engines ◽  
Temperature Heat

Low-temperature heat sources such as waste heat and geothermal energy in the range from 100 ℃ to 200 ℃ are widely available and their potential is largely untapped. Stirling engines are one possibility to convert this heat to a usable power output. Much work has been done to optimise Stirling engines for high-temperature heat sources such as external combustion or concentrated solar energy but only little is known about suitable engine layouts at lower temperature differences. With the reduced temperature difference, changes become necessary not only in the heat exchangers and the regenerator but also in the operating parameters such as frequency and phase angle. This paper shows results obtained from a third-order simulation model that help to identify beneficial parameter combinations, and explains the differences of low and high-temperature engines.

scholarly journals Environmental tests of vapor compression heat pump for space applications

2020 ◽  
pp. 240-240
Author(s):  
Xudong Ma ◽  
Rui Ma ◽  
Yilin Ye ◽  
Suying Yan ◽  
Feng Wang ◽  
...  
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Heat Pump ◽  
Low Temperatures ◽  
Heat Pumps ◽  
Coefficient Of Performance ◽  
Vapor Compression ◽  
Space Applications ◽  
Suitable Temperature ◽  
High And Low Temperatures

Heat pumps are needed to provide a suitable temperature for both people and equipment in spacecraft. This paper reports on work designed to see if vapor compression heat pumps, in particular, can be expected to function normally in space. A vapor compression heat pump was built and tested under conditions of high temperature (70?C), low temperature (0?C), and near-vacuum (10-4 Pa). It was found that the coefficient of performance of this heat pump was 2.99 at both high and low temperatures, and was 2.1 under near vacuum conditions. The results suggest that vapor compression heat pumps are suitable for use in space.

Thermodynamic Performance Analysis of Ammonia-Water Rankine Cycles Using Heat Sources of High and Low Temperatures

2012 ◽  
Vol 249-250 ◽  
pp. 278-283
Author(s):  
Kyoung Hoon Kim ◽  
Hyung Jong Ko ◽  
Se Woong Kim
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Thermal Efficiency ◽  
Low Temperatures ◽  
Ammonia Concentration ◽  
Working Fluid ◽  
Heat Sources ◽  
Ammonia Water ◽  
High And Low Temperatures ◽  
System Variables

In this study, thermodynamic performances of ammonia-water Rankine (AWR) cycle and regenerative Rankine (AWRR) cycle are comparatively investigated. Special attention is focused on the effects of ammonia concentration and turbine inlet pressure on the performance of system using heat sources of high temperature of 300 oC and low temperature of 150 oC. The behavior of important system variables including mass flow ratio of working fluid, net work production, and thermal efficiency are closely examined. Results show that performance characteristics for heat sources of high and low temperatures are quite different each other. For the high-temperature source, the thermal efficiency has a minimum in AWR system while it has a maximum in AWRR with respect to ammonia concentration in the range of 65% to 75%. For low-temperature source, however, the thermal efficiency decreases with ammonia concentration in the range of ammonia concentration higher than 95% for both AWR system and AWRR system and the effect of regenerator is negligible.

MODELING OF AN ORGANIC RANKINE CYCLE FOR LOW TEMPERATURE HEAT SOURCES

2018 ◽  
Author(s):  
Arthur Batista Martins Lott ◽  
Arthur Pacheco Luz ◽  
João Arthur Daconti Silva ◽  
Cristiana Maia ◽  
Sergio Hanriot
Keyword(s):  
Low Temperature ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Heat Sources ◽  
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 R1234yf and R1234ze as alternatives to R134a in Organic Rankine Cycles for low temperature heat sources

2017 ◽  
Vol 142 ◽  
pp. 1192-1198 ◽  
Author(s):  
Francisco Molés ◽  
Joaquín Navarro-Esbrí ◽  
Bernardo Peris ◽  
Adrián Mota-Babiloni ◽  
Carlos Mateu-Royo
Keyword(s):  
Low Temperature ◽  
Heat Sources ◽  
Temperature Heat ◽  
Organic Rankine Cycles

Relieving of Residual Stresses in Metal Workpieces at High and Low Temperatures

2021 ◽  
Vol 887 ◽  
pp. 651-656
Author(s):  
Marina V. Polonik
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Residual Stresses ◽  
Low Temperatures ◽  
Creep Properties ◽  
Processing Modes ◽  
Properties Of Materials ◽  
High And Low Temperatures ◽  
Temperature Heating ◽  
High Temperature Heating

On the basis of previously accumulated irreversible deformations, and, consequently, residual stresses, the process of removing residual stresses in metal workpieces under the action of low and high temperatures is simulated. Boundary value problems are solved and here are described regularities that are responsible for removing residual stresses for processing modes: high-temperature heating - cooling, high-temperature heating - holding - cooling, low-temperature heating - holding - cooling. The holding stage is modeled, taking into account the creep properties of materials under Norton creep conditions. According to the dependences of the obtained exact solutions, it is shown that it is the holding process that leads to the relaxation of residual stresses.

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