Dynamic whole system testing of combined renewable heating systems – The current state of the art

Abstract

For the evaluation of the energetic performance of combined renewable heating systems that supply space heat and domestic hot water for single family houses, dynamic behaviour, component interactions, and control of the system play a crucial role and should be included in test methods. New dynamic whole system test methods were developed based on "hardware in the loop" concepts. Three similar approaches are described and their differences are discussed. The methods were applied for testing solar thermal systems in combination with fossil fuel boilers (heating oil and natural gas), biomass boilers, and/or heat pumps. All three methods were able to show the performance of combined heating systems under transient operating conditions. The methods often detected unexpected behaviour of the tested system that cannot be detected based on steady state performance tests that are usually applied to single components. Further work will be needed to harmonize the different test methods in order to reach comparable results between the different laboratories. A harmonized approach for whole system tests may lead to new test standards and improve the accuracy of performance prediction as well as reduce the need for field tests.

Survey of modern pellet boilers in Austria and Germany – System design and customer satisfaction of residential installations

“…Further details on the test cycles and the obtained results were given by Schwarz et al [15] and Carlon et al [16]. For biomass based combisystems further test cycles are available [17]. The most common method is the concise cycle test [18][19][20][21] by the Institute for Solar Technology (SPF).…”

Numerical and experimental results of a novel and generic methodology for energy performance evaluation of thermal systems using renewable energies

“…The procedure for the CCT and DST method is not based on direct extrapolation, but rather on fitting a global model (usually TRNSYS software) and simulation, as in the component approach. Further detail on the comparison of the three first methods is given in [23]. Extrapolation to other boundary conditions, different from those of the test sequence, is possible with the CCT method using annual simulations on the basis of the identified parameter values for the model.…”

“…The Short Cycle System Performance Test (SCSPT), Combitest [22], Concise Cycle Test (CCT) [23] and Dynamic System Testing DST [24][25][26] are examples of this kind of method. The system is charged and discharged according to a specific standard (the case of DST) or test sequence (12 days for SCSPT and CCT, but only 6 days for Combitest) particular to each method.…”

Fixing Efficiency Values by Unfixing Compressor Speed: Dynamic Test Method for Heat Pumps

“…However, various studies exist that reproduce the seasonal performance of HPs via simulations [18,19], as well as consider the operating parameters of the units control such as the compressor frequency [20]. Menegon et al [21] and Haller et al [22] developed dynamic laboratory tests for the characterization of heating systems. Riederer et al [23] developed a dynamic test specifically for ground source heat pumps (GSHPs) considering dynamic weather conditions, occupancy profiles and a reference building.…”