Proposed approximate linear equations
In this work, approximate linear equations are derived to obtain ton, toff, D, PEWH. This achieved by doing the following steps:
Step 1. Derive equation for ton.
Replace dTH by Thigh-Tlow and dt by ton when EWH is ON in Eq. (3.1). In addition, TH(t) is assumed to be equal to Td in order to calculate the average heat losses to the ambient and due to inlet cold water replacing the water drawn from the tank. Finally, by replacing