Different channels for different refrigerants [9]

The future scenario of HP will be based on many refrigerants which belong to A2L if not A3 category. As consequence and in addition to the well-known efficiency challenges we have now to deal with a new design criterion: don' t exceed the maximum refrigerant charge! Given the refrigerant limit of A2L refrigerants set at c.a. 1,8kg and the charge limit of 150g for R290 to avoid annual inspection we have developed new channel plates to support the booming HP market. The coverage of the heating capacity without adding extra refrigerant charge is now a potential issue which can be solved by developing new channel plates with the same efficiency but different hold up volume. According to this need Alfa Laval has developed a new product for Propane HP (CB24). The A2L refrigerants imply a much better control of the freezing resistance to avoid the risk that the flammable refrigerant is going into the water loop. Alfa Laval has further developed the control of the deformation during the freezing cycle in order to secure the “zero leakage risk with A2L”. We will review the portfolio and the criteria for selecting the different channel plates like AC40, CB65 and the new product CB24. We will show the different hold up volume on the refrigerant side which helps the respect of the refrigerant charge. We will present some concrete design selection for geothermal HP and air to water HP. We will analyse the behaviour of the AC40 channel plate during the defrost and we set the criteria to control the plate deformation when ice is formed.