How to make a heat exchanger more efficient

The coolant always needs to be at a lower temperature than the hot fluid. Lower coolant temperatures will take more heat from the hot fluid compared to warmer coolant temperatures. If you had a glass of drinking water in room temperature for instance, it's much more effective to cool it down using ice rather than just cool water, then the identical principle applies to heat exchangers.

Flow speed - Another important element is the flows of the fluids in both the primary and the secondary side of the heat exchanger. A larger flow rate will increase the ability of the exchanger to transfer the heat, however a greater flow rate also means greater mass, which may make it more challenging for the energy to be eliminated as well as increasing speed and pressure loss.

Setup - The heat exchanger should be set up based on a manufacturers' guidelines. Broadly speaking the most effective way to install a heat exchanger is using the fluids flowing into a counter-current arrangement (so if the aluminium is travelling left to right, the warm fluid travels directly to left) and for shell and tube heat exchanger the coolant should enter at the lowest inlet place (as shown in the diagrams above) to make sure that the heat exchanger is obviously full of water. For air cooled heat exchangers it's important to consider the air flow when installing a cooler, any part of the core which is blocked will compromise cooling capacity.