What is cross-flow heat exchanger?
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What is cross-flow heat exchanger?
A cross-flow heat exchanger is used in a cooling and ventilation system that requires heat to be transferred from one airstream to another. A cross-flow heat exchanger is made of thin metal panels, normally aluminium. The thermal energy is exchanged via the panels.
How do you analyze a heat exchanger?
Heat exchangers are usually analyzed using either the Logarithmic Mean Temperature Difference (LMTD) or the Effectiveness – Number of Transfer Units (ε-NTU) methods. The LMTD method is convenient for determining the overall heat transfer coefficient based on the measured inlet and outlet fluid temperatures.
Where are cross-flow heat exchangers used?
A cross-flow is typically less expensive than other types of heat exchanger. It is normally used where hygienic standards require that both airstreams are kept completely separate from one another. It is often used in heat recovery installations in large canteens, hospitals and in the food industry.
How can you increase the efficiency of a cross-flow heat exchanger?
Here are 5 proven industry practices to boost heat exchanger performance and maintain process efficiency:
- Online and Offline Cleaning.
- Maintaining Heat Exchanger.
- Periodic Cleaning.
- Cleaning the PHE Manually.
- Minimizing the Fouling Factor.
- Analyzing and Addressing Issues in Heat Exchanger Efficiency.
Why are cross flow heat exchangers used?
What is the example of cross flow type heat exchanger?
Cross flow exchangers, same as shell and tube, are usually used in the two-phase systems. An example of the application is a condenser in steam systems, in which steam passes over the tubes in the shell side and changes phase to the liquid water. Cold water passes through the tubes and absorbs the heat from steam.
How does a cross flow heat exchanger differ from an counterflow one?
In counter-flow heat exchangers, the hot and the cold fluids move parallel to each other and both enter the heat exchanger at the same end of the heat exchanger and both fluids flow towards the same direction. In cross-flow heat exchangers, the two fluids usually move perpendicular to each other.
How do you calculate LMTD for cross flow heat exchanger?
To calculate LMTD: Find the temperature difference on the left side of the heat exchanger, ΔT1. Obtain the temperature difference on the right side of the heat exchanger, ΔT2. Subtract the temperature difference, ΔT2 from ΔT1.
How does a cross flow heat exchanger differ from a counter flow one?
What is the difference between mixed and unmixed fluids in cross-flow? In a counter flow heat exchanger, the hot and cold fluids enter the heat exchanger at opposite ends and flow in opposite direction. But in case of cross flow heat exchanger, the two fluids usually move perpendicular to each other.
What is the effectiveness of heat exchanger?
The effectiveness (ϵ) of a heat exchanger is defined as the ratio of the actual heat transfer to the maximum possible heat transfer.
What is the purpose of heat exchanger?
Heat exchangers are used to transfer heat from one medium to another. These media may be a gas, liquid, or a combination of both. The media may be separated by a solid wall to prevent mixing or may be in direct contact.
What is cross flow area?
The cross-flow area, Sm, is the minimum flow area in one central baffle space at the center of the tube bundle. It is calculated by the following equation: (6.17) where. B = central baffle spacing.
What is the purpose of LMTD?
The log mean temperature difference (LMTD) is used to determine the temperature driving force for heat transfer in flow systems, most notably in heat exchangers. The LMTD is a logarithmic average of the temperature difference between the hot and cold streams at each end of the exchanger.
What is the analysis relation for effectiveness of NTU for heat exchangers?
Number of Transfer Units (NTU) The NTU is a function of the Effectiveness and HCRR established by the process temperatures and flow rates and is indicative of the size of the heat exchanger needed. The greater the value of NTU, the larger the heat transfer surface area (A) required to meet the process conditions.
What are the advantages of heat exchanger?
One of the greatest benefits of modern heat exchangers is that they do not rely on additional equipment, such as an air conditioning or air compressing unit, to operate. Therefore, they use significantly less energy and produce little or no pollution compared to more conventional cooling methods.
How does cross flow filtration work?
Cross-flow filtration, also known as tangential flow filtration, separates particles in solution by passing the solution along the surface of a membrane. Liquid passes through the membrane because of the pressure differential across the membrane.
What is LMTD explain in brief?
The LMTD is a logarithmic average of the temperature difference between the hot and cold feeds at each end of the double pipe exchanger. For a given heat exchanger with constant area and heat transfer coefficient, the larger the LMTD, the more heat is transferred.
