Author(s)

Yuefen Gao, Honglei Zhao, Yingxin Peng, Tony Roskilly

School of Energy, Power & Mechanical Engineering, North China Electric Power University, Baoding, China.
Swan Center for Energy Research, Newcastle University, Newcastle Upon Tyne, UK.

HFO-1234yf and HFO-1234ze[E] have low global warming potential and zero ozone depletion potential. If they are used in the direct expansion ground source heat pump system substituting for HFC-134a, the system will be beneficial to mitigating climate change. This study aims to find out the thermodynamic characteristics of the direct expansion ground source heat pump system using HFO-1234yf or HFO-1234ze[E] by theoretical calculation. The results indicate that HFO-1234yf system in an actual cycle has the highest COP. HFO-1234yf and HFO-1234ze[E] have such smaller capacity per unit of swept volume that they need larger compression capacity if providing the same heating or cooling loads. For a given unit when HFC-134a is replaced with HFO-1234yf or HFO-1234ze[E], the capacity will decrease. More refrigerant charge is required in the HFO-1234yf or HFO-1234ze[E] system. The results also present that more refrigerant charge is required in the cooling mode than in the heating mode.

Direct Expansion Ground Source Heat Pump (DXGSHP); Thermodynamic Performance; HFO-1234yf; HFO-1234ze[E]; HFC-134a

Y. Gao, H. Zhao, Y. Peng and T. Roskilly, "Analysis of Thermodynamic Characteristic Changes in Direct Expansion Ground Source Heat Pump Using Hydrofluoroolefins (HFOs) Substituting for HFC-134a," Energy and Power Engineering, Vol. 5 No. 2A, 2013, pp. 11-17. doi: 10.4236/epe.2013.52A002.