24 June 2014

FLOWRATE DEPENDENT HEAT-PUMP MODEL


The EU’s energy efficiency strategy lead to new requirements for space-heaters. The assessment for electrically driven heat pumps is based on standard EN 14825.
Required data may be derived from established rating measurements according to EN 14511. Based on such a calculation, a refined model has been developed and successfully
validated for an air-to-water heat-pump. The algorithm is based on Carnot’s law at the refrigerant cycle. By a linear interpolation of exergetic efficiency, operating points that fall in
between rated points are made available to the calculation. The algorithm also incorporates a
functionality that estimates the behaviour of the heat exchangers. These refinements to existing models become important as rating data is usually available for operating conditions that are different from real-world conditions, where temperature spread at the sink side interacts with the load. The model is based on widely available data and can therefore be
applied to many heat-pumps. As it originally has been developed for the use in standard calculations, it’s one of its strength that results of such assessments and simulations can be
compared.