What is the difference between mixed and unmixed fluids in cross flow?

In (a) the cross-flow is said to be unmixed since the plate fins force the fluid to flow through a particular inter fin spacing and prevent it from moving in the transverse direction (i.e., parallel to the tubes). The cross-flow in (b) is said to be mixed since the fluid now is free to move in the transverse direction.

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 does a cross flow heat exchanger transfer heat?

A crossflow heat exchanger is designed so that the two fluids flow perpendicular to one another. This is typically utilized when one fluid is a liquid and the other is a gas, as in a car radiator in which hot water flowing left and right is cooled by air moving up or down, Bright Hub Engineering explained.

Why does a mixed or unmixed fluid arrangement influence heat exchanger performance?

Mixing allows the fluid to achieve uniformity more rapidly due to the increased interactions between the fluid molecules that have interacted with the exchanger surface and those that haven’t.

What is difference between parallel flow and counterflow heat exchanger?

A counter-flow heat exchanger is one in which the direction of the flow of one of the working fluids is opposite to the direction to the flow of the other fluid. In a parallel flow exchanger, both fluids in the heat exchanger flow in the same direction.

Why is a counter flow heat exchanger better than a parallel flow heat exchanger?

Counter flow heat exchangers are inherently more efficient than parallel flow heat exchangers because they create a more uniform temperature difference between the fluids, over the entire length of the fluid path. Each time a fluid moves through the length is known as a pass.

What is the most effective exchanger?

Plate exchanger is the most efficient due to turbulent flow on both sides. High heat-transfer coefficient and high turbulence due to even flow distribution are important. However, a plate heat exchanger regenerator is restricted to low viscosities.

What is not a recuperative heat exchanger?

6. Which of the following is not an example of recuperators type heat exchanger? Explanation: Recuperators are not used in chemical factories.

What is the most effective heat exchanger?

Plate exchanger
Plate exchanger is the most efficient due to turbulent flow on both sides. High heat-transfer coefficient and high turbulence due to even flow distribution are important. However, a plate heat exchanger regenerator is restricted to low viscosities.

How do you calculate effective heat exchanger?

If one of the fluids is undergoing a change of phase throughout the entire heat exchanger and at a constant temperature (i.e. heat capacity is infinite), the thermal efficiency is simply Eff=1-exp(-U.A/Cmin), where Cmin is the heat capacity (m x cp) for the single phase fluid, U-overall heat transfer coeffcient and A …

What advantage does the effectiveness NTU method have over the lmtd method?

The NTU method does not rely on using an numerical iterative solution to find the outlet temperatures of the heat exchanger, which would be the case if the LMTD method were used to find two outlet temperatures. Thus, the NTU would save much calculation time in this case.

Why are baffles used in a shell and tubes heat exchanger?

Baffles serve two functions: Most importantly, they support the tubes in the proper position during assembly and operation and prevent vibration of the tubes caused by flow-induced eddies, and secondly, they guide the shell-side flow back and forth across the tube field, increasing the velocity and the heat transfer …

Why does a mixed or unmixed fluid arrangement influence heat exchanger?

Sorry, the other answer is wrong. “Mixed” and “unmixed” refer to cross-flow heat exchangers, where the main direction of each flow is the transversal of the other. “Mixed” means than the fluid temperature is equalized in the transverse direction due to intense (turbulent) mixing, so that its temperature only varies in its the main direction.

What’s the difference between a flow and a heat exchanger?

A heat exchanger is a device that gets heat from one fluid to another. Usually hot water to atmosphere air, as in the car’s radiator. “Flow heat exchanger” refers to two liquid fluids, a “cold” one and a “hot” one.

How is heat transfer performed in a finned exchanger?

Since the tube flow is unmixed, both fluids are unmixed in the finned exchanger, while one fluid is mixed and the other unmixed in the unfinned exchanger. To develop the methodology for heat exchanger analysis and design, we look at the problem of heat transfer from a fluid inside a tube to another fluid outside.

Which is an example of a cross flow exchanger?

For examples, cross flow exchangers are ubiquitous in heating, ventilating, and air conditioning (HVAC) systems not only as cooling and dehumidification coils but also as heating coils and air-cooled condensers. They are also commonly encountered as vehicle engine radiators and in other process and component cooling and heating applications.