The Various Processes of Heat Transfer

The cooling, heating and preserving of food is vital to human survival. We must heat food, so it is safe to eat and preserve it, so it does not become rotten or diseased. There are many things we need to be able to do with food regarding thermal energy and to do this we use science, for example we insulate thermostats so the liquid in them can stay warm or cold. To change the rate of thermal energy transfer there are three main processes; conduction, convection and radiation. We can use these processes to stop and change the rate of heat transfer of our food.

The most common form of heat transfer is conduction, we use this in many different process but one of the most important is in cooking. Cooking our food is what keeps it healthy, the intense heat kills germs on the meat and other foods we eat. According to Nora Fulmer of the WebstaurantStoreblog, “Conduction is the process of heat being transferred between objects through direct contact.” (Fulmer). Conduction is used in cooking food when you use a frying pan, the burners on your stove pass heat energy into the bottom of your pan. When you place food inside your pan some of the heat energy is passed into the food, cooking it. It should be noted that conduction is one of the slowest methods of heat transfer and cannot cook the entire substance at once as the food needs contact with the bottom of the pan. According to LiveScience some chicken can house salmonella bacteria which was a major issue in 1998 to 2010, and so it is important that you cook a chicken the whole way through. We use the process of conduction to do this and this has many economical and social factors. Less people get salmonella every day, this means less people become sick and can work, this is both a social and economic factor that can be linked with using conduction in cooking.

Convection is and extremely common form of heat transfer, even if we do not realise it. We use convection often for heating, but it can also, using refrigerators, be used to keep food cold and healthy. According to the U.S. Department of Health and Human Services, “Chilling stored foods to proper temperatures is one of the best ways to slow the growth of dangerous bacteria.” (United States, Congress, House, U.S. Department of Health and Human Services). Convection occurs when particles in a liquid or gas have high energy, and take the place of particles with less energy, thus heating up the cold places while cooling the warmer places. Refrigerators take advantage of convection to keep our food cool, the refrigerator substance inside the fridge is warm, as it moves through the fridge it absorbs all the heat. When it leaves the fridge, it is warmed up by the kitchen and turns into vapor as shown in this picture. Keeping certain foods in the fridge is what allows them to stay edible and healthy for long periods of time, for example milk has to be keept cool otherwise it will go rotton and will make you sick. Fridges allow us to keep our food nice for longer periods of time than we usually would, which means we don’t have to buy food quite has often and we also do not have to eat it immediately. The invention of refrigerators brought many economic benefits, there is now more food available as it doesn’t go off as quick and people do not have to spend as much money on food. Radiation is perhaps the most important form of heat transfer, it is how the suns heat reaches through the vacuum of earth. Radiation is a form of heat transfer that uses infared waves and does not require particles to work, unlike conduction and convection.

Microwaves are used daily by many people, these machines take advantage of radiation to cook our food. The microwaves use high frequency waves that penetrate food and agitate the water molecules which, through conduction, heat up your food. Although microwaves are not necissary to survival they have a few economical and ethical factors. Microwaveable food is cheap and plentifull which is good for the less fortunate but some peopele question whether or not it is healthy to eat microwaved food. Some people believe microwavable dinners are unhealthy whereas some people use them everyday, this debate has points for both sides and can cause arguments. Regardless of whether or not they are healthy microwaves are one of the most common ways people use radiation in everyday life.