  The ground source heat pump heating system is considered as one of the best
solutions for the transition towards green heating under the continental
climate conditions like Kazakhstan. In this paper, experimental and theoretical
investigations were carried out to develop a ground source heat pump-based
heating system under the weather conditions in Kazakhstan and to evaluate its
thermodynamic performance. The water-to-water heat pump heating system,
integrated with a ground source heat exchanger and used refrigerant R134a, was
designed to provide hot water to meet the requirements for space heating. The
predicted values of the coefficient of performance and the experimental results
were found to be in good agreement within 6.2%. The thermodynamic performance
of the system was also assessed using various environment-friendly
refrigerants, such as R152a, R450A, R513A, R1234yf and R1234ze, as potential
replacements for R134a. Although R152a is found to be a good alternative for
R134a in terms of coefficient of performance and total equivalent warming
impact, its flammability hinders its application. The heating system using
refrigerants R450A, R513A, R1234yf and R1234ze shows 2-3% lower coefficient of
performance than that of R134a. The highest exergy destruction is found to be
attributed to the compressor, followed by the expansion valve, evaporator, and
condenser. Considering their low flammability and low environmental impact,
R450A, R513A, R1234yf and R1234ze are identified as valuable replacements for
R134a.
