Heat pumps enable the efficient supply of useful heat, including environmental heat (ambient air, ground). The Fraunhofer Institute for Solar Energy Systems ISE in Freiburg, Germany, has been carrying out extensive work in this area for several years – from material and component development through to system assessment and optimization. The tests involved in a qualitative analysis of two-phase refrigerants are performed on a test bench whose key component is a custom-built globe valve manifold, developed jointly by GEMÜ and the Fraunhofer Institute ISE.