COMPARISON OF THE TRANSIENT BEHAVIOUR OF MICROCHANNEL AND FIN-AND-TUBE EVAPORATORS

摘要

The development of control algorithms for refrigeration systems requires models capable of simulating transient behaviour with sensible computational time and effort. The most pronounced dynamics in these systems are found in the condenser and the evaporator, especially the transient behaviour of the evaporator is of great importance when designing and tuning controllers for refrigeration systems. Various so called moving boundary models were developed for capturing these dynamics and showed to cover the important characteristics. A factor that has significant influence on the time constant and nonlinear behaviour of a system is the refrigerant charge which is considerably reduced when microchannel heat exchangers are utilized. Here a moving boundary model is used and adapted to simulate and compare the transient behaviour of a microchannel evaporator with a fin and tube evaporator for a residential air conditioning system. The results are validated experimentally at a test rig.