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Opis: The most common current technology for producing artificial cold is based on the operation of gas compression and absorption, which was discovered more than a century ago. This technology uses refrigerants as a heat transfer agent. Magnetic refrigeration is an innovative technology that works based on the magnetocaloric effect and the properties of certain rare materials/metals. The present paper describes a simulation of the magnetocaloric effect (MCE) of a gadolinium plate (Gd.), which is the main component of the active magnetic regenerator (AMR). The first part includes a description and history of the discovery of the magnetocaloric effect of materials that possess such properties. The continuation is a COMSOL Multiphysics modelling of AMR's main component: a gadolinium (Gd) plate. The simulation of the magnetocaloric effects and the heat dispersion on its surface was done in COMSOL, as was the highlighting of the adiabatic temperature on the flat surface of the plate. Water was used as a heat transfer agent, and gadolinium (Gd) was used as a reference criterion for the materials. The model simulates a single step of the magnetic refrigeration cycle and evaluates the AMR's performance with a single board. This study enables identifying the most important characteristics that influence the active magnetic regenerator's thermal behaviour.
Ključne besede: energy efficiency, magnetocaloric material, magnetic refrigeration, active magnetic regenerator
Objavljeno v DKUM: 04.12.2023; Ogledov: 284; Prenosov: 5
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Opis: Due to limited availability of natural resources exploited for heating and in order to reduce the environmental impact, people should strive to use renewable energy sources. Heat pumps allow the conversion of ambient heat, available in almost unlimited quantities, to heating energy. The paper describes an energy-saving house provided with good thermal insulation and heated by an air-to-water split-type heat pump. The condenser is located in the attic and the evaporator in the boiler room of the house. The house heating up to the ambient temperature of 0 °C was provided by an air-to-water heat pump and a condensing oil heating furnace if the ambient temperature dropped to below 0 °C. The results of the nine-year testing showed that the heat pump was used during most of the heating season. The average coefficient of performance (COP) of the air-to-water heat pump in nine heating seasons was3.16, indicating that over 68% of the heat was obtained from the ambient air. The comparison between COP of air-to-water heat pumps in energy-saving house and of water-to-water heat pumps fitted in houses dealt with under otherprojects indicates that water-to-water heat pumps have higher COPs. The heat pumps obtain heat from groundwater, hence they are capable of operating throughout the heating season, and possess the highest COP. The advantage of an air-to-water heat pump, however, lies in its simple design and a wide rangeof applications. Due to limited availability of natural resources exploited for heating and in order to reduce the environmental impact, people should strive to use renewable energy sources. Heat pumps allow the conversionof ambient heat, available in almost unlimited quantities, to heating energy. The paper describes an energy-saving house provided with good thermal insulation and heated by an air-to-water split-type heat pump. The condenser is located in the attic and the evaporator in the boiler room of thehouse. The house heating up to the ambient temperature of 0 °C was providedby an air-to-water heat pump and a condensing oil heating furnace if the ambient temperature dropped to below 0 °C. The results of the nine-year testing showed that the heat pump was used during most of the heating season. The average coefficient of performance (COP) of the air-to-water heat pump in nine heating seasons was 3.16, indicating that over 68% of the heat was obtained from the ambient air. The comparison between COP of air-to-water heatpumps in energy-saving house and of water-to-water heat pumps fitted in houses dealt with under other projects indicates that water-to-water heat pumps have higher COPs. The heat pumps obtain heat from groundwater, hence they are capable of operating throughout the heating season, and possess the highest COP. The advantage of an air-to-water heat pump, however, lies in its simple design and a wide range of applications. In comparison to the furnace, the heat pump yielded considerable saving in fuel and monry, which justifies its home heating application in the Central European climatic area. The analys
Ključne besede: heating, energy saving houses, heat pumps, therodynamics, refrigeration
Objavljeno v DKUM: 01.06.2012; Ogledov: 2320; Prenosov: 119
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Opis: A new non-destructive method was developed for the detection of refrigerant leakage at an evaporator`s inflow. Nitrogen and oxygen gas were successively blown through the evaporator. A gas analyser was applied at the outflow of the evaporator and the oxygen concentration measured. It was possible to detect any leakage by investigating the oxygen concentration-time history diagram.
Ključne besede: refrigeration, refrigerant leakage, plate evaporator, measurements, non-destructive method
Objavljeno v DKUM: 31.05.2012; Ogledov: 1892; Prenosov: 89
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