Capacity control in ground source heat pump systems part II: Comparative analysis between on/off controlled and variable capacity systems

Modelling of a water-to-air variable capacity ground-source heat pump

“…In Table 1, fan power is included but the power of the GHX pump and the hot water tank circulator pump are excluded. As shown by Madani, Claesson and Lundqvist (2011), pumping power can be responsible for a large share of the energy consumption in variable capacity heat pumps, since they achieve longer operating time than on-off heat pumps. It is interesting to note the COP variation with compressor frequency.…”

“…In order to maintain the same mean temperature over one cycle, on-off heat pumps have to deliver heat during the on period at a higher temperature than variable capacity heat pumps, which leads to a better coefficient of performance (COP) for variable capacity machines. According to Madani, Claesson and Lundqvist (2011), sizing the heat pump to face a small fraction (under 66%) of peak load to reduce compressor cycling results in an increase in auxiliary energy consumption (electric or gas), which degrades the overall seasonal performance factor.…”

Experimental investigation on ground source heat pump system

“…The main disadvantage is the higher initial capital cost, being about 30-50% more expensive than air source units. However, once installed, the annual cost is less over the life of the system, resulting in net savings (Madani et al, 2011). In recent years, most studies have concentrated on enhancing the performance of GSHP systems, improving the accuracy of the models and design methods using thermal energy reservoirs (Zhu et al, 2014).…”

Control and energy optimization of ground source heat pump systems for heating and cooling in buildings

“…Lee [36] reported a reduction of 27% at least in the compressor energy input when adopting a variable-speed part-load control to the GSHP in both the cooling and heating mode operations. Madani et al [37] carried out a comparative analysis between ON/OFF controlled and variable capacity GSHP systems. In [38], the same author carried out a comparative analysis of three common control strategies for an ON/OFF controlled ground source heat pump system.…”

“…Solving Eq. 3.58 for T SB (2nd order equation), for dierent values of the partial load ratio (α = [0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1]) and dierent values of the ambient temperature(T amb = [24,25,26,27,28,29,30,31,32,33,34,35,36,37,38] • C), Fig. 3.42 can be obtained.…”