Optimizing Heat Transfer for Industrial Settings | Wattco
Last updated on July 3rd, 2023 at 06:57 pm
Conduction heating has its place for certain industrial processes, but it’s crucial industrialists use this heating method correctly. That means using the most suitable heating methods, materials, and calculations to ensure there’s maximal heat transfer for a given application. Find out what the best heat transfer methods for industrial settings are, and the measures industrialists can take to increase efficiency.
Conduction
Heat transfer only happens through conduction, convection, or radiation. Conduction is the most common method found in day-to-day life, such as heating blankets, touching a warm window pane, or seat warmers in cars. This means heat energy is absorbed by a surface which makes its molecules vibrate quickly. Touching one warm surface to another will transfer that same energy, thus creating heat transfer through conduction.
Conduction depends on the temperature gradient (how the temperature changes in a location), cross sections of the materials, path lengths, and material properties. Heat will always flow from whichever material is warmest to the colder one until both materials are at the same temperature, reaching thermal equilibrium.
Convection
Heat transfer through convection will heat the air molecules immediately surrounding the heat source (like radiators and storage heaters). When the air heats up, it rises, leaving room for cooler air molecules to approach the heat source and repeat the same process. The warm air will transfer its heat to cooler molecules, gradually heating up the space.
Radiation
Radiant heaters emit infrared radiation that will travel until it comes in contact with a solid object. Any object that’s hit with this heat will start to warm up. For example, the heat from the sun will travel straight to the ground so long as there aren’t any obstacles in its path. Radiation heat transfer doesn’t depend on other molecules or contact to spread warmth; it will send heat energy outwards and whatever is warmed by the radiation will then warm the space around it.
Conductive heat transfer applications
Conductive metals are used in electronics and mechanical components to either draw or deflect thermal energy. These methods can be used for medical devices, laboratory equipment, construction, gear, electrical wiring, and more.
Maximizing heat transfer for all three methods
Using the best metals
Different types of metal will have different abilities in terms of thermal conductivity. Some metals will be so bad at heat transfer they’re used as insulators. Other metals are much better at producing and spreading heat. These metals would be used for cookware, for example.
Aluminum offers a lightweight, cheap, and easy-to-use metal for thermal conductivity. While silver is excellent, copper is another great option for thermal conductivity and is cheaper and more readily available than silver. Copper is corrosion and biofouling resistant making it a great option for solar water heaters, industrial heaters, and heat pumps, for example.
Understanding heat boundaries
When solving the differential equation governing heat conduction in a body, it’s necessary to apply boundary conditions at the edge of the analysis domain to obtain a solution. The three common boundary conditions are:
1. Constant temperature
For the constant temperature boundary condition, the surface temperature is assumed to remain at the specified value. Regardless of how much heat passes through the surface. In general, the specified surface temperature can change with time, and can also be different for distinct points on the boundary.
Physically, constant temperature boundary conditions are often approximated very well by phase change (boiling, melting, condensation, etc.) at the surface. The energy associated with phase change absorbs or supplies large amounts of heat at the phase change temperature.
2. Constant heat flux
For the constant heat flux case, the heat flux at the surface is assumed to remain at the specified value regardless of what happens to the temperature. Again, in the most general case, the heat flux can be a function of time and position.
Over a limited range of temperatures, a constant heat flux boundary condition might be approximated by a thin electrical resistance heater, or by radiative heating from a source that is at a much, much higher temperature than the surface.
A well-insulated surface constitutes a special case of a constant heat flux boundary condition where the heat flux is specified as zero. This is called an adiabatic surface.
3. Convection
A convection boundary condition occurs when the surface is exposed to convective heat transfer governed by Newton’s law of cooling. The convective heat transfer coefficient and the free stream temperature could, in general, both be functions of time and position. A simple example of one-dimensional, steady-state heat transfer can illustrate the effect and application of different boundary conditions.
Choosing the best heaters and accessories for conduction
Circulation heaters
Circulation heaters, also known as “in-line heaters,” have uses in many applications. They can use steel, stainless steel, or titanium depending on the application. Lube oil and waste oil applications often use steel for circulation heaters. This is because it’s inexpensive compared to its stainless steel counterpart. Water circulation heaters use stainless steel because of its anticorrosive qualities.
In both applications, a pump flows the liquid, such as water or glycerol, through a closed pipe circuit. The liquid is reheated as it flows through the circulation heater. A major consideration for this application is viscosity. Electric circulation heaters generate heat, making the medium less viscous. The less viscous the fluid, the easier it is to pump through a circuit of pipes.
Immersion heaters
Industrial immersion heaters are a fast and efficient way of heating various liquid solutions in processing equipment, as well as in large tanks through the use of tank immersion heaters. Heating liquids using direct heat transfer allows for the liquid medium to quickly reach the desired temperature using electric heating elements, such as flanged heaters, screw plug heaters, over-the-side heaters, or immersion water heaters.
Tubular heating
Tubular heating elements from Wattco are the most versatile and the best-suited industrial heating solution for a large number of applications. Tubular elements from Wattco are factory-configured to almost any shape or size.
Custom bending diameters can be made upon request and we can manufacture a variety of industrial heating solutions, such as flanged tubular heaters. Tubular heaters are typically made using steel, stainless steel, Incoloy, Inconel, or titanium alloys.
Tubular elements are often regarded as the foundation of all heating elements. These heating elements have a strong outer sheath to help protect the process heater from physical stress and use high-quality alloys to allow efficient heat transfer from the resistance coil to your heating medium.