An online optimum control method for magnetic cooling systems under variable load operation

Abstract Magnetic cooling system has a significant energy saving benefit, if the part load operations can be properly leveraged. In this study, an online optimum control method is proposed that not only automatically maintains the temperature of the cold heat exchanger, but also provides additional efficiency enhancement since the optimum utilization factor is determined based on the instant operating conditions in real time. Numerical simulations are carried out to characterize the steady state performance map. The database of the optimum utilization factor is then developed based on it. When applying the optimum utilization factor to the control method, both the transient responses during the start-up process and the variable load operation are evaluated. It is found that the proposed online optimum control method introduces an additional transient loss, due to the simultaneous adjustments of frequency and utilization factor.