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In this contribution, a dynamic test method to determine the seasonal performance of invertertype air conditioners has been developed and verified. In comparison to current test standards, where test modes for fixing the compressor speed are required, a dynamic approach is applied with unfixed compressor speed and thus better reflects the performance of air conditioners under real operating conditions. The dynamic tests are conducted in two calorimeter chambers. The indoor chamber is kept at a constant temperature whereas the outdoor chamber is subjected to a temperature profile based on the climate BIN-distribution, representing the reference cooling demand. The proposed dynamic test considers the dynamic control of an air conditioner and delivers results which could indicate the units’ performance in the field.
In this contribution, a dynamic test method to determine the seasonal performance of invertertype air conditioners has been developed and verified. In comparison to current test standards, where test modes for fixing the compressor speed are required, a dynamic approach is applied with unfixed compressor speed and thus better reflects the performance of air conditioners under real operating conditions. The dynamic tests are conducted in two calorimeter chambers. The indoor chamber is kept at a constant temperature whereas the outdoor chamber is subjected to a temperature profile based on the climate BIN-distribution, representing the reference cooling demand. The proposed dynamic test considers the dynamic control of an air conditioner and delivers results which could indicate the units' performance in the field.
The growing market penetration of heat pumps indicates the need for a performance test method that better reflects the dynamic behavior of heat pumps. In this contribution, we developed and implemented a dynamic test method for the evaluation of the seasonal performance of heat pumps by means of laboratory testing. Current standards force the heat pump control inactive by fixing the compressor speed. In contrast, during dynamic testing, the compressor runs unfixed while the heat pump is subjected to a temperature profile. The profile consists of the different outdoor temperatures of a typical heating season based on the average European climate and also includes temperature changes to reflect the dynamic behavior of the heat pump. The seasonal performance can be directly obtained from the measured heating energy and electricity consumption making subsequent data interpolation and recalculation with correction factors obsolete. The method delivers results with high precision and high reproducibility and could be an appropriate method for a fair rating of heat pumps.
In this study, the test method EN 14825 for testing air conditioners is validated by verifying the sensitivity of the seasonal energy efficiency ratio SEER (declared on the energy efficiency label) in relation to the nominal cooling capacity Pdesign. Therefore, the two major parts of the test method, the measurement part and the calculation part, were investigated. Measurements were conducted on several single-split units. The calculation part was subjected to a sensitivity analysis in order to identify the properties of an air conditioner which have a strong influence on the SEER. The analysis revealed that the measurement procedure delivers reproducible results. However, the energy consumption in special operating states, the duration in active-mode and seasonal performance values in active mode (SEERon) significantly affect the sensitivity of the SEER. Especially assumption of short operating times for a cooling active mode leads to large changes in the SEER with varying Pdesign. In addition, the range of power of Pdesign turned out to have an increasing impact on the SEER with decreasing Pdesign. For Pdesign values ≤10 kW, which is the most popular type of ACs in the EU, the sensitivity of the SEER increases tremendously.
Especially the determination of the SEER for devices with short operating times in cooling active-mode (350 h) and low values for Pdesign (≤10 kW) cannot be reproduced anymore. In consequence, manufacturer could use the sensitivity of the SEER on Pdesign to artificially “increase” the energy efficiency of their air conditioner for the Energy label about 10 %.
To determine the seasonal performance of heat pumps for energy labelling this study proposes a two-point-method that could conceivably be an alternative to the European standard EN 14825 and similar test standards such as ISO 13256. Heat pumps were tested in line with the EN 14825. The reduction of measurement points, from between five to seven (EN 14825) to only two (two-point-method), leads to 60 % savings in cost and time. It is shown that the shortened method can be used to determine the seasonal energy efficiency of heat pumps with the same degree of precision compared to EN 14825.
Minimum energy performance standards and labels are commonly used tools to reduce the household energy use thus mitigating greenhouse gas emissions. However, the technical foundation for minimum energy performance standards and labels are test procedures for rating and testing of appliances. To de- termine the seasonal cooling performance of air conditioners, the current test standards require fixing of the compressor speed of the units to achieve steady-state conditions; this way of operation, how- ever, differs from real-life use. To make the seasonal cooling performance testing better reflect the real use conditions, this study proposes a compensation method which can be conducted independently from manufacturer data and still allows modulation of the tested units. Our results show that the tested units behave differently under part-load conditions, which results in a lower energy efficiency rating for some of the tested devices.