Heat Pumps Today

16 February | March 2022 W H I T E P A P E R ( https://www.haustechnikdialog.de/ SHKwissen/1410/ Spezifische-Heizlast ). This leads to absolute heating capacity requirements of between 5 to 8kW for heating systems in new buildings (including sanitary hot water requirements) and of 10 to 15kW for heating systems in existing buildings, also including sanitary hot water usage. Temperature Level Requirements In residential applications and new buildings, Heat Pumps often operate at 35°C for underfloor heating and 60 °C for sanitary hot water. In cases of building renovations, higher temperatures are necessary to replace fuel or gas boilers, with about 55°C for radiator heating and 60°C for sanitary hot water. The target is to provide univalent solutions so as to avoid e…ciency losses due to usage of direct electrical heaters, and to avoid an increase in CO 2 emissions due to the adoption of an additional gas boiler at low outside temperatures. This requires a high temperature lift at low environmental temperatures, e.g. from -25 °C to +60 °C. Crucially, this required high temperature lift cannot be provided by all refrigerants. Performance Comparison of Refrigerants For the purposes of this paper, a calculation tool was developed to compare the performance of di‹erent refrigerants for Heat Pump applications. The aforementioned tool, developed in Excel®, uses Refprop 10.0 (Reference Fluid Thermodynamic and Transport Properties) for calculating fluid properties. It is based on basic thermodynamic equations linking pressure, temperature, enthalpy and entropy to establish the capacity and coe…cient of performance (COP) of a thermodynamic cycle. Drop-in tests performed on Air to Water (A/W) (R-410A) and Brine to Water (B/W) (R-407C) Heat Pumps by the Fraunhofer ISE Institute demonstrate that simply changing refrigerants without any modification to the Heat Pump system generally does not lead to any performance improvements. Under some operating conditions, the drop-in refrigerant(s) performed better than the original, whereas under other conditions, the performance worsened. The discrepancies between theoretical performance calculations and actual test results from drop-in trials have been reported by Küpper et. al. (2021). Operating range of R-410A, R-454B, R-452B, R-454C and R-32 (compressor envelopes) Today, R-410A can be taken as a standard reference refrigerant for Heat Pump applications. With dedicated technologies like enhanced vapor injection or enhanced liquid injection (EVI / ELI) it is possible to achieve the requested temperature lift of between -25°C to +60°C. This is su…cient for new buildings, which require 35°C water temperature for underfloor heating and 60°C for sanitary hot water. At lower only for new buildings, but for renovation projects as well. This is particularly important in Europe, as the proportion of building renovations compared with new builds is quite significant. For building renovations, high flow temperatures (for existing radiator-based heating systems) are essential for convenient and cost- and energy-e…cient replacements of fossil fuel boilers, eliminating the need for additional electric or fossil-fuel booster heaters during the colder months. Although there is significant potential for increasing system e…ciency by using A2L refrigerants, drop-in tests have shown that utilizing a high-performance refrigerant in a standard Heat Pump system, while possible, does not provide the e…ciency gains of a purpose-built system. For maximum energy economy and environmental benefits, Heat Pump systems should be designed around refrigerants, not in isolation. Special Considerations for Building Renovation Heating Capacity Needs For a typical new Central-European construction, heating requirements are around 35 W/m 2 . While for existing buildings, depending on the degree of thermal insulation, a relative heating capacity of 100 to 150W/m² is estimated