Experimental study of solution defrosting characteristics of air source heat pump

Air source heat pumps are widely used due to their high efficiency, energy-saving, and environmentally friendly nature. However, frost accumulation on heat exchanger surfaces restricts their application in regions with low temperatures and high humidity. Additionally, existing defrosting methods have certain limitations. To address these issues, this study presents a defrosting solution rooted in the chemical potential theory. The defrosting mechanism is first scrutinized through this theory. Subsequently, a system for air source heat pump solution defrosting is devised, along with a simulation test setup to explore defrosting characteristics utilizing sodium formate (HCOONa) solution. Outcomes reveal the efficacy of sodium formate in eliminating exchanger frost. Sustaining air circulation during defrosting could expedite frost layer removal and shorten the defrosting duration. Moreover, greater spray flow rate, temperature, and defrosting solution concentration correlate with reduced defrosting time. Notably, in this experiment, the defrosting amounts for the two experimental conditions were essentially the same at the time points of 90 s, 180 s, and 270 s at solution concentrations of 25% and 30%. This indicates that further increasing the solution concentration does not significantly accelerate the rate of frost melting.

Automated summary

Air source heat pumps are widely used due to their efficiency, energy-saving, and environmentally friendly nature. However, frost accumulation on heat exchanger surfaces limits their application in low-temperature and high-humidity regions. This study presents a defrosting solution rooted in the chemical potential theory, which utilizes sodium formate solution to effectively eliminate exchanger frost. Results show that sustaining air circulation, increasing spray flow rate, temperature, and solution concentration can all shorten the defrosting time.