secondary loop, automotive HVAC, PCM, Modelica
Within the framework of the energy management of passenger cars new driving concepts like those with start-stop-mode require an adaption of the HVAC system. Indirect systems with secondary loops might be a possibility to face these new requirements. As a part of the European “TIFFE” project (Thermal Systems Integration for Fuel Economy) a secondary loop system for mobile HVAC applications is currently in development. Among other things, the project pursues the realization of a compact and hermetic refrigeration unit called CRU with two secondary loops. Through applying a CRU some relevant advantages like the implementation of flammable or toxic refrigerants, the easy exchangeability of the HVAC system, or lower refrigerant charges might be achieved. Within this publication the modeling of the whole system as well as a CRU test rig with two secondary loops will be shown. Experimental and simulation results will be presented. For the cycle simulation the advanced Modelica library TIL Suite will be used. By utilization of a virtual test drive the influence of different climatic conditions and operation conditions like start-stop-mode will be shown. Part of the work at the Technische Universität Braunschweig within the TIFFE project deals with the use of phase change materials (PCM) for heat and cold storage implemented in the secondary loops. Macro-encapsulated paraffin could be one promising type of PCM for mobile applications. Measurement results for this kind of material and the influence of the PCM on the whole system will be presented.