Enhanced interlaboratory reproducibility of emulator-type load-based tests

The feed-forward compensation (FFC) method for the emulator-type load-based testing was developed to ensure adequate trackability of the return air condition in test facilities, thereby improving the reproducibility and standardization of dynamic test results. A linearized model of thermal and transport delays within the testing facility forms the basis for the recalibration of temperature and humidity control signals from the room emulator to the reconditioning unit of the psychrometric chamber. To achieve reproducibility levels comparable to current steady-state tests this study develops a model formulation that minimize chances of unstable control of the testing environment, practically deploys the FFC technique in interlaboratory tests, and demonstrates its effectiveness. Consequently, its implementation on a 10 kW ceiling-cassette-type unit demonstrated improved trackability, leading to delays and deviations from the emulator signal limited to 60 s and 0.1 K, respectively. It is demonstrated that delay compensation generally reduced sources of results variability on repeated measurements in the same testing environment. Interlaboratory results show deviations in the recorded coefficient of performance within 2% for all investigated testing conditions during both cooling and heating operation. The proposed method does not require additional equipment and is therefore proposed to enhance the reliability of current testing equipment in conducting precise and reproducible dynamic tests.