Tag: heat

Heat Transfer (Conduction, Convection, Radiation)

Published on by Jordan T ShouseLeave a comment

Thermal energy moves from warmer regions to cooler ones through conduction, convection, and radiation. Objects continuously lose heat until they achieve thermal equilibrium, meaning they reach the same temperature as their environment. For instance, a steaming mug of tea will gradually cool until it matches the temperature of the room.

But how that mug looses that heat is what this blog is all about.

CONDUCTION:

Thermal energy moves through solids mainly via conduction. This phenomenon happens when two solid items with varying temperatures come into contact, enabling heat to transfer from the warmer object to the cooler one. For instance, in the scenario of a hot coffee mug resting on a cold table, the thermal energy shifts from the mug to the table beneath it.

CONVECTION:

Convection refers to the movement of fluids, whether they are liquids or gases, and can occur naturally or be induced by external forces. Fluids can either absorb or release heat, depending on their temperature. Natural convection happens due to variations in density; for instance, steam rises from the top of the mug as the steam rises, colder air is cycled in.

RADIATION:

While the coffee emits infrared radiation as it loses heat, this process is generally less significant compared to conduction and convection in the context of a cup of coffee. This type of heat loss can be felt by holding your hand near a warm coffee cup as shown.

No matter how the heat is transferred to an object, if it needs to be cooled there is a good chance that one of our Application Engineers has approached a similar issue and can help. To discuss, contact us, and we will walk through the best method to eliminate the heat from within your application.

Jordan Shouse
Application Engineer

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It’s Getting Hot In Here!

Published on by Brian FarnoLeave a comment

Okay, if you did not finish the song lyrics when reading the title, it’s okay, we can still be friends. In all actuality, the temps are warming up here in the MidWest as we prepare for our false Spring as indicated by the freezing temps and snow we received earlier this week. There is one thing that has stayed constant and that is the methods of heat generation.

1 – Kettle-convection-conduction-radiation

Heat generation is a result of energy conversion. The conversion of energy to do work, whether it is actual voltage going through a transformer that operates a neon sign to light up the roadside sky or energy from a hydraulic ram that is compacting recycled paper into a bundle and the hydraulic fluid is being pressed in and out of cylinders from a pump, all of it will have some form of a heat byproduct. This heat then gets transferred and how it is transferred can be helpful to know.

2 – Energy Transfer – Heat

At the molecular level, atoms store the energy that will cause electrons to enter into an excited state and rapidly switch between shells. When the electron returns to a lower shell (closer to the nucleus), energy is released; the energy released is then absorbed by atoms at a lower energy state and will continue until the thermal energy is equal between the two objects. Heat has four fundamental modes of transferring energy from surface to surface, and they are as follows:

Advection
Advection is the physical transport of fluid from point A to point B, which includes all internal thermal energy stored inside. Advection can be seen as one of the simpler ways of heat transfer.

Radiation
Radiation is the transfer of thermal energy through empty space and does require a material between the two objects. Going back to how thermal energy is released from atoms when the electron returns to a lower energy shell, the energy is released in the form of light ranging from infrared light to UV light. Energy in the form of light can then be absorbed by an object in the form of heat. Everyone experiences radiation transfer every day when you walk outside; the light from the sun’s radiation is what keeps this planet habitable.

Conduction
Conduction can also be referred to as diffusion and is the transfer of energy between two objects that have made physical contact. When the two objects come into contact with each other, thermal energy will flow from the object at the higher temp to the object at the lower temp. A good example of this is placing ice in a glass of water. The temperature is much lower than the room temperature. Therefore, thermal energy will flow from the water to the ice.

Convection
Convection is the thermal energy transfer between an object and a fluid in motion. The faster the fluid moves, the faster heat is transferred. This relies on the specific heat property of a molecule to determine the rate at which heat will be transferred. When a molecule has a lower specific heat, it takes faster motion and larger volumes to achieve the full effect of convection transfer. Convection is used in modern ovens to get a more even heat throughout the food while cooking.

No matter how the heat is transferred to an object, if it needs to be cooled there is a good chance that one of our Application Engineers has approached a similar issue and can help. To discuss, contact us, and we will walk through the best method to eliminate the heat you need to.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

1 – “Kettle-convection-conduction-radiation” by P.wormer is licensed under CC SA 3.0
2– “Energy Transfer – Heat” by Siyavula Education is licensed under CC BY 2.0

Fundamental Modes of Heat Transfer

Published on by Brian FarnoLeave a comment

Generally I like to write about cool stuff. Whether it is a new product like our TurboBlast Safety Air Gun, an application that really helped cool down a process for a customer, or even something cool I have done like a GORUCK event or training. Well, today is not one of those days, today we are going to talk about the opposite of cool … HEAT and more importantly the methods it is transferred.

1 – Energy Transfer – Heat

The process of how heat is generated all starts with a conversion of energy. Whether it is friction, or converting energy to light, or even converting energy to a different voltage through something like a transformer. No matter how it is generated, heat will begin to transfer. On the molecular level, atoms are storing the energy which will cause electrons to enter into an excited state and rapidly switch between shells. When the electron returns back to a lower shell (closer to the nucleus) energy is released; the energy released is then absorbed by atoms at a lower energy state and will continue until the thermal energy is equal between the two objects. Heat has four fundamental modes of transferring energy from surface to surface and they are as follows:

Conduction
Conduction can also be referred to as diffusion and is the transfer of energy between two objects that have made physical contact. When the two objects come into contact with each other thermal energy will flow from the object with the higher temp to the object with the lower temp. A good example of this is placing ice in a glass of water. The temperature is much lower than the room temperature therefore the thermal energy will flow from the water to the ice.

Radiation
Radiation is the transfer of thermal energy through empty space and does require a material between the two objects. Going back to the how thermal energy is released from atoms; when the electron returns to a lower energy shell the energy is released in the form of light ranging from infrared light to UV light. Energy in the form of light can then be absorbed by an object in the form of heat. Everyone experiences radiation transfer every day when you walk outside; the light from the sun’s radiation is what keeps this planet habitable.

Convection
Convection is the transfer of thermal energy between an object and a fluid in motion. The faster the fluid moves the faster heat is transferred. This relies on the specific heat property of a molecule in order to determine the rate at which heat will be transferred. The low the specific heat of a molecule the faster and more volume of the fluid will need to move in order to get full affect of convection. Convection is used in modern ovens in order to get a more even heat through out the food while cooking.

Advection
Advection is the physical transport of a fluid from point A to point B, which includes all internal thermal energy stored inside. Advection can be seen as one of the simpler ways of heat transfer.

No matter how the heat is transferred to an object, if it needs to be cooled there is a good chance that one of our Application Engineers has approached a similar issue and can help. To discuss, contact us and we will walk through the best method to eliminate the heat you need to.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

1 – “Energy Transfer – Heat” by Siyavula Education is licensed under CC BY 2.0

Radiant Heat- Where Does It Come From

Published on by Brian FarnoLeave a comment
Even in extremely aggressive environments, EXAIR Cabinet Cooler Systems provide reliable heat protection for your sensitive electronics and controls.

The three types of heat transfer have been discussed here and there on this blog before. One of the most common heat transfer methods that I deal with on a day to day basis is radiant heat transfer. Also known as thermal radiation, the process is actually the exchange of energy by photons. The main difference separating radiant heat from convection and conduction is that radiation does not require there to be a medium to permit propagation of the heat. Any item which contains thermal energy, meaning it is above absolute zero and less than 1,000 Kelvin, will have this thermal energy. This thermal energy is radiated to other items causing a transfer of heat energy to those objects that results in an equilibrium between the items. The equilibrium does not stop the transfer of photons however.

The most common occurrence that most of us get to experience for radiant heat is heat from the Sun. As the sun shines it is emitting heat. On a hot day, generally the sun is a little closer to your geographic location and you feel hot because the sun is emitting more heat onto your surface than what is being emitted by your internal temperature, so your core temp will increase. On a cold day, when the sun is further away, while it is still shining you feel cold because the sun is not in fact transferring as much energy to the surface of your body than what you are internally generating. The same kind of radiant heat transfer can be from a campfire, open kiln, maybe even a hot steel slab coming out of a blast furnace.

The model 1126SSW 1″ Flat Stainless Steel Super Air Nozzle w/ Swivel Fitting cools a flame sensor within an industrial furnace.

Understanding where a radiant heat source is being generated can help tremendously when looking at cooling an electrical enclosure or even trying to keep a part or sensor cool. Radiant heat is one of the few times a heat shield or shade structure can help to eliminate a portion of the heat load being introduced. Other methods to combat the heat load would be determined with the application at hand. For cooling enclosures that are absorbing a solar heat load, we would look at an EXAIR Cabinet Cooler System and the factors that help to appropriately size the cooler. If this is a single component or part, we would evaluate one of the many other EXAIR Engineered Solutions to determine the best fit for the application. To do either of these, all it takes is a simple chat, email, or call to an Application Engineer.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF