Study on the Performance of New High Temperature Heat Pump Mixtures as Alternatives to R245fa

Abstract

Purposes At present, the contradiction between energy supply and demand is increasingly intensifying, and high-temperature heat pumps, as an energy-saving and emission-reduction technology, can upgrade a large amount of low-grade waste heat to high-grade energy for utilization. Methods Five environmentally friendly heat pump working fluids are proposed, R1233zd(E)/R1234ze(Z)(0.15:0.85), R600a/R1233zd(E)(0.70:0.30), R600a/R1233zd(E)/R600(0.01:0.15:0.84), R600a/R1233zd(E)/ethylene oxide (0.34:0.01:0.65), and R1233zd(E)/R1234ze(Z)/R245ca/R600a (0.39:0.58:0.01:0.02). The performance of the new working fluid and the existing working fluid R245fa is compared in terms of basic thermophsical properties, cycle performance, and safety. Findings The results show that the five alternative working fluids proposed are superior to R245fa in terms of viscosity, constant pressure specific heat, thermal conductivity, and condensation heat, and have outstanding environmental performance. For the cycle performance, under the condition of condensing temperature of 110 ℃, the alternative working fluid COP is close to R245fa, and the unit volume of heat production is 111%, 144%, 125%, 144%, and 108% of R245fa, respectively. The group contribution method is used to predict the flammability of the new working fluid, and the results show that R1233zd(E)/R1234ze(Z)(0.15:0.85), R600a/R1233zd(E)(0.70:0.30), and R1233zd(E)/R1234ze(E)/R245ca/R600a (0.39:0.58:0.01:0.02) are estimated to be non-flammable mixtures. Conclusions All the five working fluids have the potential to replace R245fa, and R1233zd(E)/R1234ze(Z) (0.15:0.85) is the most recommended, which has good comprehensive performance.

Keywords

• heat pump
• working fluids
• cycle performance
• flammability
• gwp