大多数制冷盘管在温度低于32°F（0°C）的空间中冷却空气时都会结霜。如果不从翅片盘管上取下，这种霜最终会阻塞空气通道，导致制冷能力损失。除霜盘管有几种方法（电加热器、暖风、水等），其中一种流行的方法是热气除霜。由于节约能源的动机持续增长，越来越多的过程受到审查，以确定其能源影响。 热气除霜过程影响制冷设备所需能量的两个主要方式是:（1）除霜所需的冷凝压力；（2）除霜过程利用高压气体中的能量融化霜的效率。

Frost forms on most refrigeration coils that cool air in spaces at temperatures below 32°F (0°C). If not removed from a finned coil, this frost will ultimately block the passage of air causing a loss in refrigeration capacity. There are several methods of defrosting coils (electric heaters, warm air, water, etc.)* and one of the popular methods is hot-gas defrost.Because the incentive to conserve energy continues to grow, more and more processes come under scrutiny to determine their energy implications. The two major ways in which the hot-gas defrost process affects the energy required by the refrigeration plant are (1) the condensing pressure required by the defrost, and (2) the efficiency of the defrost process in using the energy in the high-pressure gas for melting the frost.