Life cycle cost analysis of ground-coupled heat pump systems including several types of heat exchangers

Abstract

Ground-Coupled Heat Pump (GCHP) systems are now becoming very popular in both residential and commercial applications because of their great advantages as compared to conventional electrical air conditioning systems. They require less energy for operation, conserving the energy, and the most important reason is that these are environmentally-friendly systems. Currently, there are four types of heat exchangers introduced to practical application; however, there are no commercial programs that can depict the operating behavior of all the four heat exchangers. Based on an equivalent diameter introduced by Gu and O’Neal (1998), this thesis suggests an equivalent diameter model to estimate the borehole thermal resistance. Moreover, this thesis gives the assessment of other variables in sizing and operating GCHP systems for all types of heat exchangers. One of the most important problems in evaluating the GCHP systems is optimizing the Life Cycle Cost (LCC) of GCHP systems. Yeung (1996) firstly proposed LCC optimization model to roughly estimate the LCC of GCHP systems with single U-type heat exchangers. However, in this optimization, only single U-type heat exchanger was considered. Moreover, the optimization did not take into account the effect of pipe sizes on the heat pump and neither considered the capacity of the heat pump. In this thesis, a new model of LCC optimization with new improvements was proposed to optimize the LCC of GCHP systems in consideration with the effect of pipe size and capacity of the heat pump for not only single U-type heat exchanger but also for double, triple U type and coil-type heat exchangers.