Modeling the demand of a Calorifier to establish the baseline before retrofitting it with a commercial air source heat pump

Abstract

In South Africa, more than 40 % of the electricity generated by Eskom is used by the commercial sector. The universities constitute the primary consumers of electrical energy through the utilization of hot water. The research focused on the construction of a data acquisition system that monitored the demand and hot water profiles of a 12.0 kW Calorifier. The DAS comprised of 1 current transducer that measured current, hence determined the power consumption, 3 temperature sensors that measured the inlet cold water, outlet hot water into the residence and the room temperature and also a flow meter that measured the volume of incoming cold water into the Calorifier. In addition a regression model was also developed correlating the energy consumption during the heating up cycle to the total volume of cold water flowing into the Calorifier, the average room temperature, the average inlet, the outlet water temperature as well as the time taken for the heating up cycle. The reliefF algorithm was used to rank the predictors by weight of importance to the energy consumed. The results depicted that on an average weekday for the month of March 2013, a volume of 1953 L of hot water was drawn and an electrical energy of 137.85 kWh was consumed with a load factor of 0.464. Furthermore the reliefF algorithm showed that all the predictors were primary factors except of the room temperature. The mathematic model could always be used in adjusting the baseline, when computing the energy saving after retrofitting the Calorifier with an ASHP.