A heat exchanger is a piece of equipment that allows heat to be transferred, from one medium to another.
Heat exchangers are classified into two types:
• Direct heat exchange, in which both mediums come into direct contact with one another. For example, a cooling tower in which water cools through direct contact with air.
• Heat exchange via divided media in an indirect manner.
The heat transfer theory between mediums and fluids occurs when:
1. Heat is always transferred from a hot medium to a cold medium,
2. The mediums must always have a temperature difference,
3. The amount of heat lost by the hot medium equals the amount of heat gained, by the cold medium.
How is a Heat Exchanger built?
To choose a heat exchanger, we need to know the following:
• Primary circuit fluid type, temperature, and flow rate (usually the hot fluid),
• What you wish to remove from the primary circuit (Heat dissipation or a target outlet temperature),
• Fluid type, temperature, and flow rate in the secondary circuit (usually the coolant).
What fluids can a Heat Exchanger handle?
The suitability of a fluid for use with a heat exchanger is determined, by the type of heat exchanger used and the materials available. Most fluids, including oil, water, water glycol, and sea water, are suitable for standard heat exchangers.
Other materials, such as Stainless Steel and Titanium, must be used for more corrosive fluids, such as chlorinated salt water, refrigerants, and acids.
What is temperature Cross Over?
Temperature cross over refers to the situation in which the temperatures of both circuits, in a liquid-cooled heat exchanger begins to cross over. This is an important consideration in heat exchanger design, because the efficiency of a cooler is significantly reduced when temperatures cross over.
For applications where temperature cross over cannot be avoided, a plate heat exchanger is often the best option.
How can a heat exchanger be made more efficient?
Heat exchanger efficiency can be defined in a variety of ways, but there are several key factors to consider, when it comes to thermal performance.
• Temperature differential - The difference in temperature between the hot fluid and the coolant is critical, when designing a heat exchanger. Always keep the coolant at a lower temperature than the hot fluid. Lower coolant temperatures absorb more heat from hot fluid than higher coolant temperatures.
• Flow rate - The flow rate of the fluids in both the primary and secondary sides of the heat exchanger is another important factor. A higher flow rate increases the exchanger's ability to transfer heat, but it also means more mass, which can make it more difficult to remove energy, while also increasing velocity and pressure loss.
• Installation - The heat exchanger should always be installed according to the manufacturer's instructions. The coolant should enter at the lowest inlet position, to ensure that the heat exchanger is always full of water.
When installing a cooler for an air-cooled heat exchanger, it is critical to consider the air flow; any part of the core that is blocked will reduce cooling capacity.
If you have any questions about wastewater treatment plants, or if you would like to discuss about heat exchangers and their use in various manufacturing industries or WWTPs, please contact the Netsol Water team right away. Our team is an expert in water treatment and can help you tailor a solution to your specific requirements.
We collaborate with our clients to design a customized water treatment solution that meets your specific requirements, as well as an on-going service plan to completely or partially maintain your system.