Thermistor ntc sensor inaccuracies impact on the hvac/r compressor performance

Abstract

Electricity consumption for thermal comfort in urban buildings is estimated to an average of 35%. The aim of this article is to evaluate, theoretically, the impact of sensors inaccuracies on the performance and efficiency of HVAC equipment. Different types of temperature and pressure sensors are considered. The measurement tolerance, from manufacturer’s technical data sheet, will be used for the theoretical evaluation of the range in which the operating point of the equipment can vary. Compressor selection software are used for evaluating theoretical COP and electrical energy consumption change in the range of sensor inaccuracies. The study evaluates theoretically the impact on performance of scroll, piston and screw compressors, considering refrigerants used in chillers (R717, R134a, R410A, R32). The operating point of the compressor is considered as normal chiller scenario, with evaporation temperature of +4oC and condensing pressure corresponding to +35oC. The conclusion of the theoretical evaluation is that resistance tolerance bigger than 1% brings a 1% or more variation of compressor’s performance.