Which method is effective for increasing the efficiency of forced convection?

Using fans to enhance fluid flow is an effective method for increasing the efficiency of forced convection. In forced convection, fluid movement is driven by an external force, typically a fan or pump. This increased velocity of the fluid allows for greater heat transfer rates because the fluid can absorb heat more quickly as it moves across surfaces. When airflow is enhanced, it reduces the thermal boundary layer thickness near the heat exchange surface, which leads to improved heat transfer coefficients.

In contrast, reducing the fluid's temperature, while it might lower the heat content, does not inherently improve convection efficiency. Decreasing the surface area of heat exchangers negatively impacts heat transfer because there is less area for the heat exchange to occur. Using thicker fluids generally results in higher viscosity, which can inhibit fluid flow and reduce convection efficiency, making the heat transfer process less effective.