Refrigerated trucks require regular defrosting to maintain optimal cooling performance. One key reason for the truck’s interior temperature cooling down slowly is the low heat transfer efficiency of the evaporator, which is usually caused by thick frost or excessive dust on its surface. Since the evaporator’s surface temperature is often below freezing and the compartment’s temperature is relatively higher, moisture from the cargo or air easily freezes on the evaporator, affecting its heat exchange efficiency. To address this, the evaporator needs regular defrosting. Here are three common methods for defrosting a refrigerated truck:
1. Manual Shutdown Defrosting
This method involves turning off the compressor and opening the compartment door to allow the temperature to rise. As the compartment warms, the frost will melt naturally. Once the frost has melted, the compressor can be restarted.
2. Water Spray Defrosting
After removing the cargo from the compartment, warm water is sprayed onto the evaporator’s pipes to dissolve or remove the frost. This method is useful not only for thick frost but also for cleaning dust accumulation, which can also reduce the evaporator’s heat transfer efficiency.
3. Hot Gas Defrosting
Hot gas defrosting is a widely used and efficient method in the refrigeration industry. Through a controller in the driver’s cab, a defrosting solenoid valve is activated to direct high-temperature refrigerant gas from the compressor into the evaporator. This melts the frost on the evaporator. This method is highly effective, quick, and reduces labor intensity. It is simple in design and offers more thorough defrosting. A defrost sensor is installed on the low-pressure side of the refrigeration system to monitor the defrost temperature. A thermostat controls when defrosting stops, ensuring accurate timing and optimal defrost results. This guarantees consistent cooling performance, protecting the quality of goods inside the truck.
Regular defrosting not only ensures better refrigeration efficiency but also helps maintain the quality of perishable goods transported in the truck.
