Interview Tech Tip!! Almost all mechanical engineering roles require an understanding of heat transfer. Thermal considerations are always present, whether you are designing a rocket ship, laptop, kitchen table, or anything in-between. The applications can vary widely, so often interviewers only ask about the very highest level of thermal concepts during interviews.
In the world of heat transfer, it is an extremely common technical question to be asked to name and explain the three types of heat transfer. A sufficient answer will first start off by noting that the three types of heat transfer are conduction, convection, and radiation.
We’ll take a second here to look more at convection, which is the process of heat transfer by bulk movement of a fluid as either a liquid or a gas. Convection is governed by Newton’s Law of Cooling (shown to the right), and this equation will be very valuable to recall during interviews. Being able to reference equations and their names during interviews is a quick way to show the interviewer that you possess true technical chops and strong fundamentals.
Most importantly, being able to note how to manipulate the equation to increase heat transfer due to convection is even more valuable to interviewers. From the equation to the right, you can see that increasing the surface area of contact between the two media of interest or similarly choosing a medium with a higher heat transfer coefficient will increase the resulting heat transferred.
This explains why heat sinks have many fins with ample exposed area, and also points to why they are often made of aluminum or copper as opposed to cast iron or steel.
Being able to weave these details into your response, such as the governing equation, the effects of manipulating its variables, and a real-world example, are all fantastic ways to fully show the interviewer that your fundamental understanding is more than sound for the job.
