Determination of defrosting start time in an air-to-air heat pump system by frost volume calculation method

Computer Vision Technology for Monitoring of Indoor and Outdoor Environments and HVAC Equipment: A Review

“…The current stage of frost observation research is focused on improving the original grey value calculation method and creating new frost characteristic parameters in order to achieve more accurate and timely defrost control strategies. Yoo et al [257] used measured data from an ASHP system to estimate the amount of frost per unit time step and the total amount of frost, to reasonably determine the best defrost start time when system performance decreased. Zheng et al [258] proposed a new temperature-humidity-image (T-H-I) defrost control method.…”

Study on Heating Energy Efficiency and Optimization of Solar-air Source Heat Pump

“…The results showed that a collector using corrugated pipes and a nanofluid containing 4% CuO/H 2 O could achieve a 78.25% increase in heat transfer coefficient. Woo et al [8] introduced a frost calculation method for determining the initiation time of defrosting ASHP units, and the effectiveness of this approach was confirmed through experimental data validation. Zhang et al [9] analyzed the technical feasibility and economic practicality of a lowtemperature ASHP in extremely cold areas using mathematical modeling methods.…”

A modeling study on the revere cycle defrosting of an air source heat pump with the melted frost downwards flowing away and local drainage

“…To avoid mal-defrosting phenomenon mentioned by Wang et al [17], defrosting control strategies were also widely investigated [18,19]. The time-based start defrosting [20] and temperature-based end defrosting control strategies are experimentally investigated by Song et al [21,22]. For the reported ASHP unit, the most suitable pre-set time and temperature for reverse cycle defrosting is at around 55 min and 18.5 °C, respectively.…”