For a double-effect evaporator, the heat transfer function is indispensable; without it, the evaporator is nothing but a heap of scrap metal, having no value. During actual use, many factors may affect the heat transfer of a double-effect evaporator. Below, we will delve into the specific factors that can impact the heat transfer of a double-effect evaporator.

What Factors Affect the Heat Transfer of a Double-effect Evaporator?

Typically, from a thermodynamic perspective, refrigerant entering the evaporator after throttling and under the evaporation pressure Po is usually in a liquid or a liquid-vapor mixture state. The refrigerant absorbs heat from the cooled medium through the heat transfer wall, thereby lowering the temperature of the cooled medium. Meanwhile, the refrigerant liquid boils and vaporizes into saturated vapor or superheated vapor at a relatively stable low temperature and pressure, which is then drawn into the refrigerator after passing through the evaporator output.

In a different perspective, from the perspective of heat transfer, although there are various forms of evaporators, they generally belong to the cross-flow heat exchangers, where the refrigerant and the cooled medium exchange heat on both sides of the heat exchange wall. On the refrigerant side, the refrigerant absorbs heat through the phase change of vaporization. On the other side, the cooled medium continuously flows through the heat exchange wall, releasing sensible or latent heat as required by the process and then being cooled, liquefied, or frozen.

Evaporators are typically the primary heat exchange equipment in refrigeration systems. Like condensers, the heat transfer efficiency of an evaporator depends on its heat transfer surface area, heat transfer temperature difference, and heat transfer coefficient. For a selected evaporator, the heat transfer surface area is fixed, so the focus is mainly on improving the heat transfer coefficient, in addition to appropriately increasing the heat transfer temperature difference. The enhancement of the heat transfer coefficient is influenced by factors such as the thermophysical properties of the cold and hot fluids, their flow conditions, the characteristics of the heat transfer surface, and the structural performance of the evaporator. Similarly, analyzing these factors is beneficial in taking corresponding measures during the design, installation, management, and operation and maintenance of the evaporator to enhance its heat transfer efficiency.

Here are some factors that can affect the heat transfer in a double-effect evaporator. Generally, factors impacting heat transfer in evaporators are unavoidable, but we can minimize their impact on the heat transfer of the double-effect evaporator during daily operation.