Effects of magnetocaloric wire on increase in magnetic refrigeration cycle.

The phase-out of chlorofluorocarbon (CFC) and hydrochlorofluorocarbon (HCFC) refrigerants has recently been underway with greater awareness of the environment. Given this background, magnetocaloric refrigeration technology is considered a candidate among new refrigeration technologies that comply with regulations regarding the substances. Magnetic refrigeration systems are more efficient in theory than vapor compression type refrigeration systems and are free of CFC and HCFC refrigerants. The purpose of this study was to increase the cooling power of magnetocaloric refrigerators by increasing the cycle frequency and put them to practical use. Although other researchers reported that their experiments were conducted at a frequency of several Hz, we assume that a frequency greater than 10 Hz is required to gain a power output of several kW. However, when the cycle frequency is set to a higher value, the pressure losses in the flow paths increase, resulting in insufficient cooling power to transfer heat efficiently. Consequently, we have developed a wire-shaped magnetocaloric material (MCM) using gadolinium (Gd). The configuration of wires has been considered suitable to reduce pressure losses and secure a large contact area in an active magnetic regenerator (AMR). However, working the MCM has been considered difficult. The performance of the wire-shaped MCM was measured using an experimental device. The result showed a specific cooling power of 300 W/kg at 10.0 Hz. This result was four times larger than that of Gd particles.