Modelling Magnetocaloric Heat Pumps

Abstract

Magnetocaloric heat pumps are those types of heat pumpswhich use a solidMagnetoCaloricMaterial (MCM) in place of a refrigerant to provide the work for the heat pump. MCMs are materials whose temperature changes on the application or removal of a magnetic field. This effect is known as the MagnetoCaloric Effect (MCE). Magnetocaloric heat pumps have the potential in replacing the conventional vapour compression technology for Dutch dwellings, since they have minimum environmental impact due to the absence of the coolant fluids that can harm the environment. A model of the regenerator of the magnetocaloric heat pump is developed in this project having in mind the application of this type of heat pumps to Dutch dwellings. The magnetic field that is used in the development of the model is 0.875 T, with permanent magnets being the source of the magnetic field. A sensitivity analysis is carried out in order to obtain the methods to optimize the regenerator for improving the performance of the heat pump. The performance of the heat pump is measured through its average cooling capacity, average heating capacity, temperature span and Coefficient of Performance (COP) for heating. TheMCM used for the regenerators is Gd with a totalmass of 1.18 kg. The parameter that influences the performance of the heat pump the most is the porosity of the regenerator. The heat losses through the casing have the least impact on the performance of the regenerator. The frequency of the cycle also has a profound impact on the heating capacity and cooling capacity up to temperature spans of around 18 K, but it does not have such an impact on the heating COP. After increasing the frequency, decreasing the particle diameter and decreasing the porosity, the heating capacity and the temperature span are optimized. For a temperature span of 15 K, the heating capacity is 164.2W, and for a temperature span of 20 K, the heating capacity is 99.1W.