Applied Industrial Energy and Environmental Management

Optimal flow control of a forced circulation solar water heating system with energy storage units and connecting pipes

“…The system to be optimized is a residential forced circulation SWHS that consists of an array of six flat plate solar collectors connected to a circulation fluid storage tank, which in turn is connected to a water tank as shown in figure 3.1. [5,7,26]). …”

“…Any connecting pipe with a surface that is hotter Department of Electrical, Electronic and Computer Engineering University of Pretoria than the surrounding will experience heat losses as well as energy losses [5]. Suitable pipe thermal insulation is a general solution that is used to reduce these losses in order to improve the overall thermal performance of SWHS with connecting pipes [5,26]. In most SWHS models that exist, pipe thermal losses are neglected as they are assumed to be insignificant.…”

“…where D 1 , D 2 and D 3 are the pipe insulation diameters as shown in fig.3.2, k pipe and k insulation are the thermal conductivity of the pipe and insulation material, h in , and h out are the heat transfer coefficients of the inner and outer surface of the pipe [26].…”

“…Pipe insulation is a popular method used to improve the thermal performance of a pipe. It is therefore necessary to model insulation on a pipe in order evaluate a pipes thermal performance [26]. The pipe thermal loss and decrease in temperature are characterised using equations from [5,26,29,30].…”

“…where: L is the length of the pipe, D 3 the outer diameter, U p is the pipes overall heat loss coefficient, T in is the pipes inner temperature and T a is the ambient temperature [26,30].…”