Measurements of the cooling capacity and efficiency on ceiling mounted cooling systems

For the cooling of refrigeration chambers and cold rooms are ceiling mounted cooling units from different manufacturers in various output ratings on the market available .To qualify these devices in terms of their technical performance data a test scenario was developed. By this methodology, which are based on the testing standards DIN EN 14511: 2013 for air conditioners, liquid chilling packages and heat pumps with electrically driven compressors for space heating and cooling and on the older DIN 8942: 1995 builds for integrated refrigeration units, a direct comparison can be made.The concept for the test methodology was necessary because currently no measurement standard for these device specifications exists. It is to be recognised, that a large discrepancy appears between the data sheet specifications and the measurement results. The amount of the determined deviation, shown in the following table,  is different and depends on the manufacturer. For devices for deep freezing, the determined deviations are shown in the table below. * shown value = power consumtion of the compressor (no fan and controller consumtion included).
The test methodology was applied to all devices. With several pretest measurements were checked the reproducibility of the results. The variation of the measurement results was significantly below 5%, based on the measured cooling capacityIn addition to our measurements, a device was measured comparing on another teststand outside the ILK. The deviation of the determining cooling capacity between the two test stands was also significantly below 5%. Thus it can be assumed that the test method is suitable for determining device cooling capacities.  The measurement results are representative for the test stand and thus provide a good basis for direct comparison between the devices.Information about the test setup and the implementation of the measurements can be found here!In result of the measurements must be noted that the technical datas on the nameplate and the measured performance data in parts considerably deviate of each other. The measurement results are summarized in the following table. The device names specified in the tables are made anonymous by the testing laboratory.From the perspective of the testing laboratory, the results indicate that is urgent need to catch up  to make legislative requirements for performance measurements.A uniform implementation of the measurements should be the basis for the comparability of technical datas from different manufacturers. Thus, ultimately to provide the basis for trust in the performance specifications on name plates.  Only if the performance datas match the real achievable cooling capacities  the final customer is able to reach the technical cooling task in the required quality and reliable implementation.