Study On Measurement Uncertainty And Error Analysis Of Air Conditioner Performance-testing

In science experiments and practical engineering, every measurement has its error. In order to get better measurement result, error should be analyzed. For the inevitability and universality of error, which couldn't be eliminated completely. The test result should be assessed by means of the measurement of uncertainty to determine the trustworthy degree.The error is analyzed for the test result of air conditioner performance-testing bench. The character and sources of the error should be recognized and dealed with the test data correctly to make the test result close to the true value possibly. At the same time, in order to obtain a better measurement result in case of the lowest initial investment and maintain cost, the measurement scheme and test instruments were chosen according to the measurement of uncertainty. Confronting these questions upsides, the discussions and researches as follows were carried out in this dissertation.(1) The principle error of air enthalpy difference method was analyzed theoretically. It's indicated that the error of enthalpy value will be produced when the constant-pressure specific heat of dry-air and water vapor are considered to be fixed; and it is also indicated that the test-error of the heat exchanger performance will also exist when there are condensation water in the refrigeration test condition.(2) The measurement error of nozzle unit was analyzed and investigated in terms of a large of experiment data and test principle of mass flux measurement. It is concluded that different combinations of nozzles and layout way of pressure-obtaining stomata will induce the asymmetry of airflow form and produce the flux measurement error. After a series of improvement, the standard measurement uncertainty of flux test has decreased from 8.4316m~3/h to 0.7809m~3/h, and the precision of measurement has been raised greatly.(3) The measurement uncertainty of test instruments for the enthalpy difference room has been assessed with the measurement uncertainty theory. It is presented that the influence of the wet bulb temperature of air outlet of the indoor equipment on heat transfer performance test is the largest, then the dry-bulb temperature of return air outlet and the pressure difference between the nozzle inlet and outlet, while the influence of static pressure is relatively small. According to their influence factors, the right measurements and equipments could be chosen to minimize the initial investment and service cost under satisfying the measurement precision.