22 May 2008

NEW LOW CHARGE HEAT PUMP USING PROPANE: DESIGN AND EXPERIMENTATION


The design and the experimental performance of an innovative heat pump using
propane and having a heating capacity of about 100 kW are presented in the paper. This unit
has been designed for laboratory tests and has been realized in the framework of the
European project SHERHPA in collaboration between University of Padova and Hiref SpA.
Since propane is a flammable fluid, charge minimization is a priority in the design of such
heat pump. Prototype shell-and-tube heat exchangers using minichannels and providing low
charge have also been installed in the unit, along with conventional brazed plate heat
exchangers, in order to compare different working configurations.
Very similar values of coefficient of performance and heating and cooling capacities have
been measured when using the minichannel condenser instead of the brazed plate heat
exchanger, even if this device provides a 65 % reduction in terms of condenser internal
volume and the propane charge reduction is about 0.8 kg.
The experimental performance was also measured when adopting a minichannel internal
heat exchanger showing in this case a slight improvement of the coefficient of performance.