Defrosting heaters are key components in refrigeration systems, especially in freezers and refrigerators, where their role is to prevent frosting on the evaporator coils. The buildup of frost layers can significantly reduce the efficiency of these systems, ultimately affecting their cooling capacity.
The refrigerator defrosting heating tube is an important part of the refrigerator refrigeration system, which is mainly used to melt the frost layer accumulated on the evaporator in the automated frost cycle to ensure the refrigeration efficiency of the refrigerator.
Defrost heater function:
defrosting: During the operation of the refrigerator, the surface of the evaporator will frost, and too thick frost layer will affect the refrigeration effect. The defrost heater tube melts the frost layer by heating, so that the evaporator can return to normal working state.
Automated frost: Modern refrigerators are usually equipped with automated frost systems in which the defrost heating tube will start at a set time or under a set condition and automatically turn off after defrosting.
The working principle of the defrost heater is to heat the evaporator coil at specific time intervals to melt any accumulated frost. The commonly used defrost heaters mainly fall into two types: electric heating type and hot gas heating type.
Electric defrost heaters are typically installed in household refrigerators and freezers. These heaters are made of resistance elements such as nickel-chromium alloys, which have high resistance and can generate heat when current passes through them. They are ingeniously placed near the evaporator coils or directly installed on the coils.
When the refrigerator is running in the refrigeration cycle, the evaporator coils absorb heat from the inside, causing moisture in the air to condense and freeze on the coils. Over time, this forms a layer of frost. To prevent excessive frost accumulation, the defrost timer or control board will periodically initiate a defrost cycle, usually every 6 to 12 hours, depending on the model of the refrigerator.
When the defrost cycle is initiated, the control system will cut off the compressor and activate the defrost heater. Current passes through the heater, generating heat to warm up the evaporator coils. As the coil temperature rises, the accumulated frost begins to melt and turn into water droplets.
To prevent system damage and ensure efficient defrosting, the defrost thermostat monitors the temperature of the evaporator coil. Once the temperature reaches a certain level, indicating that the frost has fully melted, the thermostat sends a signal to the control system to stop the defrost cycle.
The water formed from the melting frost flows down the evaporator coil to the drip pan located beneath the appliance. There, it usually evaporates due to the heat generated by the compressor during the normal refrigeration cycle.
On the other hand, hot gas defrosting systems are more common in large commercial refrigeration equipment. In these systems, instead of using electric heaters, the refrigerant itself is utilized to defrost the coils. During the defrosting cycle, the refrigeration system changes its operating direction.
A valve directly introduces the high-temperature and high-pressure refrigerant gas discharged from the compressor into the evaporator coil. As the hot gas flows through the coil, it transfers heat to the frost layer, causing it to melt. The melted water is drained away. After the defrosting cycle ends, the valve redirects the refrigerant back to its regular cooling circuit.
Whether it is an electric defrosting system or a hot gas defrosting system, their aim is to remove the frost layer on the evaporator coil, but they adopt different defrosting mechanisms.
Regular maintenance and normal operation of the defrost heater tubes are crucial for the efficient functioning of the refrigeration system. A malfunction of the heater may lead to excessive frost accumulation, reduced refrigeration efficiency, and potential damage to the equipment.
Defrost heaters play a crucial role in maintaining the optimal performance of the refrigeration system by preventing frost from forming on the evaporator coils. Whether through resistance heating or hot gas heating, these heaters ensure that the coils do not frost over, allowing the system to operate efficiently and maintain the required temperature inside the appliance.
Post time: Mar-22-2025