Is parallel flow or counterflow more effective?
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 maximum possible effectiveness for a parallel flow heat exchanger?
50%
For a parallel flow heat exchanger, maximum value of effectiveness that can be achieved is 50% irrespective of values of its heat transferring area and overall heat transfer coefficient.
Why is parallel flow not effective?
Parallel Flow Heat Exchanger In a parallel flow setup, both the hot fluid and cold fluids are travelling in the same direction as each other. This will still cool the hot fluid down by a considerable amount but is not as efficient as the counter flow system.
What is the effectiveness of heat exchanger?
The heat exchanger effectiveness is defined as the ratio of actual heat transfer to the maximum possible heat transfer. NTU is a measure of the effectiveness of the heat exchanger.
What are the advantages of a parallel flow system?
Parallel flow is similar to a electrical parallel circuit in which several parallel flow circuits of equal length connect to a supply header and a return header. A benefit of parallel is that a small diameter pipe can be used due to lower pressure drops and same money on installation.
Which heat exchanger is most efficient?
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.
On what factors effectiveness of heat exchanger depends?
Effectiveness of the heat exchanger depends on the thermal conductivity and convective heat transfer coefficient of the fluid.
How does heat exchanger effectiveness change with heat capacity ratio?
Effectiveness of heat exchanger decreases as capacity ratio increases. Maximum heat transfer occurs when capacity ratio is unity and therefore ε*Cr curves given as a function of NTU (number of transfer units) for Cr = 1 for various heat exchanger types.
Which flow is better in heat exchanger?
The counter-flow heat exchanger has three significant advantages over the parallel flow design. First, the more uniform temperature difference between the two fluids minimizes the thermal stresses throughout the exchanger.
How does parallel flow heat exchanger work?
This flow arrangement is called parallel flow. Heat is transferred from the warm fluid through the wall of the inner tube (the so-called heating surface) to the cold fluid. A heat exchanger can also be operated in counterflow, in which the two fluids flow in parallel but opposite directions.
When would you use a parallel flow heat exchanger?
The design of a parallel flow heat exchanger is advantageous when two fluids are required to be brought to nearly the same temperature.
What is the use of parallel flow heat exchanger?
While parallel flow arrangement can be beneficial, under certain conditions that reduce the limiting temperature, channeling problems can occur or freeze may be caused at shutdown. Thus, parallel flow in heat exchangers minimizes the chance of freezing or channeling, but does not eliminate the possibility of either.
What are the examples of cross flow heat exchanger?
The Crossflow Heat Exchanger A car radiator and an air conditioner evaporator coil are examples of crossflow heat exchangers.
Which type of heat exchanger is more efficient?
The plate type heat exchanger is the most efficient type of heat exchanger with its low cost, flexibility, easy maintenance, and high thermal transfer. WCR plate corrugations are designed to achieve turbulence across the entire heat transfer area. This produces the highest possible heat transfer coefficients…
What is the purpose of the heat exchanger?
Purpose. Heat exchangers are used to transfer heat from a fluid on a side of a barrier to a fluid on the other side without allowing the fluids to mix together. Heat exchangers maximize the surface area of a wall that is used between the two fluids while minimizing any resistance to the flow of a fluid through the exchanger.
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.