Which is better parallel flow or counterflow?
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 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.
Which flow type is the most efficient flow type?
Counter flow heat exchangers are the most efficient of the three types. In contrast to the parallel flow heat exchanger, the counter flow heat exchanger can have the hottest cold- fluid temperature greater than the coldest hot-fluid temperatue.
What is a parallel flow?
A parallel flow pattern, also referred to as a cocurrent flow, is one in which the shellside and tubeside fluids flow in the same direction. This is widely seen in double-pipe heat exchangers and can be replicated in shell and tube heat exchangers as well, according to Bright Hub Engineering.
What is parallel flow and crossflow heat exchanger?
For a given flow rate and at the given inlet and outlet temperatures, a parallel flow heat exchanger requires maximum flow area, whereas a cross flow, heat exchanger, requires minimum flow area, and a counter flow heat exchanger area lies between two extreme limits.
What is NTU in heat exchanger?
NTU is defined as:[11.74]NTU=UACminwhere U is the overall heat transfer coefficient (kW/m2K), A is the heat transfer area of the heat exchanger (m2) and Cmin is the smallest thermal capacity of the two fluids (kW/K).
Why is parallel flow not efficient?
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.
How does a counterflow heat exchanger work?
Counterflow just takes one stream and reverses it. This means that as the hot fluid enters from the right, it cools against the already warmed up cold fluid from the left. The temperature differential is nowhere near as high as at the start of the parallel 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 is better a counterflow or parallel flow heat exchanger?
A counterflow heat exchanger will require less heat exchange surface area than a parallel flow heat exchanger for the same heat transfer rate and the same inlet and outlet temperatures for the fluids. This is because the log mean temperature difference is greater for a counterflow heat exchanger.
When does parallel flow and counterflow become moot?
The concepts of counterflow and parallel flow become moot when phase change is present, and the energy balance for the side experiencing phase change becomes: Where hfg is the heat of vaporization or heat of condensation for the fluid undergoing phase change and m is the mass flow rate at which the fluid is condensing or boiling.
What kind of flow pattern is parallel flow?
A parallel flow pattern, also referred to as a cocurrent flow, is one in which the shellside and tubeside fluids flow in the same direction. This is widely seen in double-pipe heat exchangers and can be replicated in shell and tube heat exchangers as well, according to Bright Hub Engineering.
What are the disadvantages of parallel flow design?
The temperature profiles of the two heat exchangers indicate two major disadvantages in the parallel-flow design. First, the large temperature difference at the ends (Figure 10) causes large thermal stress. The opposing expansion and contraction of the construction materials due to diverse fluid temperatures can lead to eventual material failure.