La convection It is a process that occurs in nature by which heat is transferred between liquid, gaseous substances or liquid with liquid, solid and liquid, etc. All these combinations are possible when we talk about this heat exchange process in which both bodies, regardless of their state, will have different temperatures. Convection is an important process in meteorology that involves a heat transfer between air masses. If you want to learn about these atmospheric phenomena, you may also be interested in information on convection currents and about the cold weather and the heat.
Do you want to know more about convection? In this article we will explain everything about it.
Heat transfer
Heat transfer is the main thing in convection. It does not matter the state of each body, As long as there is a noticeable temperature difference, convection can occur. This is a process that we take advantage of to heat the water in a pot. When two bodies at different temperatures meet, what we know as heat flow takes place. It is the body with the highest temperature that transfers the heat to the least.
This is one of the reasons why, when we put our hand near the stove, we feel the heat. The stove is not transferring that heat. There are also other heat transfer processes such as radiation and conduction that are explained in conjunction with convection, so we will also review them later.
Both liquids and gases are considered fluids. The movement of their molecules is responsible for the heat being able to establish a flow between the two bodies. Poor thermal conductivity forces the mass to extract or release heat. To do this, it cools or heats the solids or liquids. This principle is fundamental to understanding how phenomena such as typhoon formation and how heat waves affect.
Boilers use a heat exchanger. This consists of a metal tube through which water circulates. Outside, we will have gas at a very high temperature. Through the convection process, the gas can transfer its heat to the metal tube, and the water will receive it through conduction. The tube heats up and transfers heat to the water circulating in the other direction. This water, upon receiving heat through convection, heats up until it turns into steam. You can also learn more about the relationship between heat and temperature at this link: the relationship between heat and temperature.
Driving
One of the most frequently discussed topics when it comes to energy is both direct and indirect heat transfer. In household electrical appliances we use heating and air conditioning to transfer heat or cold. These appliances also have their energy losses. The global between the amount of energy we use and that we lose qualifies as energy efficiency and it is an important variable to take into account in the final price of a product.
Driving is the process that is easily understood by everyone. Is about a heat transfer between two points that are at different temperatures. This transfer occurs without any exchange of matter between them. A simple example is: we have a metal bar with one end at 80 degrees and the other at room temperature. If there are no other external influences, heat transfer will occur by conduction from the hot end to the cold end. This will cause the cold end to eventually heat up. Needless to say, conduction depends entirely on the type of material we are talking about. Talking about a metal bar is not the same as talking about a wooden one. Conductivity is an element to take into account in this physical process of energy exchange.
Radiation
Another process by which heat is exchanged is radiation. We also use it heavily in the home. It is the heat that a body emits because of its temperature but without even contact between the bodies. We saw that in conduction there must be friction between bodies or extension of heat through the same body. What could not have was matter exchange. In this case, the warmer body can warm to the cold without even touching it.
In this type of process we will see a heat exchange by the simple fact that a body is hotter than another. For this process to be perceived, the hottest body must be at a very high temperature. A simple example of this can be seen in summer when you go to the beach. When you leave your car parked and the hours pass, you go back to get something and when you touch the metal of the doors, you get burned from how hot it is. The Sun is very far away, yet, through radiation, it is able to transfer that heat to the car. It is also interesting to know how this relates to meteorological phenomena, such as clouds. cumulonimbus and how heat waves can influence these clouds.
In the case of radiation we also take into account the type of material we are dealing with. A wooden surface heats up but is unable to store as much heat due to its insulating properties.
Types of convection
Once we have explained the possible heat transfers that exist, we are going to count the types of convection that exist. Heat transfer by convection can occur in several ways and they are:
- Forced: It is carried out through a fan, in the case of air, or a pump, in the case of water, in which the fluid moves through a hot zone and heat is transported to a cold zone.
- Natural: occurs when the fluid extracts heat from the hot zone and modifies its density. This causes it to move towards the coldest area where it will give up its heat.
To better understand the different types of convection, let's give an example. If we turn on a radiator, we have to wait for the temperature to increase. If we hold our hand over the radiator from a short distance, we'll see a completely natural air flow, since hot air tends to rise. The surrounding air heats up and decreases in density, making it weigh less. Thus, it flows upward, causing the air to pass through again, continuously renewing itself. Also, if you're interested in the effects of convection rain, you can read more at convective rains and how heat waves occur.
I hope this information helps you learn more about convection and heat transfer.
Hi. I just read the good article on convection. An illustration of a campfire is included and what would be the transfer of heat by RADIATION, CONVECTION AND CONDUCTION. The realization of the transfer by radiation and conduction I understand it perfectly, what is difficult for me to visualize is the difference between RADIATION and CONVECTION. I do not see difference between one and the other, except that one goes upwards while the radiation towards the side. The two forms would not be by convection or radiation?
Should I understand that convection is ALWAYS up and not sideways?
I appreciate any comments that help me understand this.
I thank you in advance for your time and good disposition.
Best regards