Advantages: While the temperatures T (of the cooled fluid) and t (of the warmed fluid) in the parallel flow heat exchanger can only approach each other, they can pass each other in the counter flow (Tout < tout) and in this case there has to be more heat been transferred.
Beside this, what is the advantage of counter flow system?
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.
Subsequently, question is, what is parallel flow? In the parallel-flow arrangement, the hot and cold fluids enter at the same end, flow in the same direction, and leave at the same end. counter-flow arrangement. In the counter-flow arrangement, the fluids enter at opposite ends, flow in opposite directions, and leave at opposite ends.
Subsequently, question is, 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. For example, one fluid may make 2 passes, the other 4 passes.
Which type of heat exchanger is more efficient?
Each of the three types of heat exchangers (Parallel, Cross and Counter Flow) has advantages and disadvantages. But of the three, the counter flow heat exchanger design is the most efficient when comparing heat transfer rate per unit surface area.
18 Related Question Answers Found
What is fouling factor?
Fouling Factors in Heat Exchangers. The fouling factor represents the theoretical resistance to heat flow due to a build-up of a layer of dirt or other fouling substance on the tube surfaces of the heat exchanger, but they are often overstated by the end user in an attempt to minimise the frequency of cleaning.
What is counter flow system?
counterflow system. the flow of water and blood in opposite directions across the gills of fish which ensures that blood meets water with the highest possible oxygen content. see COUNTERCURRENT EXCHANGE. Collins Dictionary of Biology, 3rd ed.
Why can countercurrent flow achieve almost 100% oxygen transfer?
In countercurrent exchange, the water and blood are flowing in opposite directions. In short, transfer of oxygen in a countercurrent exchange system can be almost 100% efficient – twice the maximum efficiency of a concurrent exchange system – with a simple reversal of the direction of flow for one of the fluids.
Why log mean temperature difference is used?
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 co current flow?
co-current flow is the flow in which both the fluid streams enter the equipment in the same direction whereas for in the counter-current flow the streams enter at opposite ends of the equipments. Co-current flow is preferred in rare cases of heat transfer where a quick heat transfer is required.
Why is countercurrent more efficient than co current?
Whereas in a counter current flow, the mean temperature differences between the two streams are negligible in fluctuation and fairly consistent. When you take the LMTD (logarithmic mean temperature difference) in the 2 cases, the value is higher in a counter current flow than a co current flow.
What is NTU in heat exchanger?
From Wikipedia, the free encyclopedia. The Number of Transfer Units (NTU) Method is used to calculate the rate of heat transfer in heat exchangers (especially counter current exchangers) when there is insufficient information to calculate the Log-Mean Temperature Difference (LMTD).
What is the difference between crossflow and counterflow cooling towers?
Crossflow cooling towers distribute the hot water perpendicularly to the air flow. Counterflow cooling towers also distribute water from the top of the tower thru pressurized spray nozzles, however the air flow is parallel (but in opposing direction) to the flow of water.
How does flow rate affect heat transfer?
In other words, the rate of heat transfer is directly proportional to mass flow rate. If you increase the flow rate, you will then increase the rate of heat transfer. Then, from the relationship above, increasing the mass flow rate must result in a smaller delta T because Q remains constant.
What is the overall heat transfer coefficient?
The overall heat transfer coefficient, or U-value, refers to how well heat is conducted through over a series of resistant mediums. Its units are the W/(m2°C) [Btu/(hr-ft2°F)].
What is double pipe heat exchanger?
In its simplest form, the double pipe heat exchanger, (also known as a concentric pipe, hairpin, jacked pipe and jacketed U-tube heat exchangers), consists of a single tube mounted inside another. One fluid flows in the inner pipe, while a second fluid flows in the outer pipe annuals.
Why is countercurrent exchange important?
Fish gills use a design called ‘countercurrent oxygen exchange’ to maximize the amount of oxygen that their blood can pick up. Oxygen would quickly pass from the water into the blood, until the oxygen levels of the blood and water rapidly became the same, and oxygen diffusion into the blood would stop.
What are the types of heat transfer?
The three types of heat transfer Heat is transfered via solid material (conduction), liquids and gases (convection), and electromagnetical waves (radiation). Heat is usually transfered in a combination of these three types and seldomly occurs on its own.
What are the different types of heat exchanger?
What are the different types of heat exchanger? Parallel-flow and counter-flow heat exchanger. Finned and Unfinned tubular heat exchanger. U-tube, single pass straight and two pass straight heat exchanger. Plate-and-frame heat exchanger. Pate-fin heat exchanger. Microchannel heat exchanger.
What are the types of heat exchanger?
Some of the types of shell and tube heat exchangers available include helical coil heat exchangers and double pipe heat exchangers, and some of the applications include preheating, oil cooling, and steam generation.
Is boiler a heat exchanger?
Since exchange of heat occurs in the Boilers, Boilers can be termed as a Heat Exchanger. But there’s more to a Boiler, than just being a Heat Exchanger. But A Boiler generates heat through chemical reaction of the fuel, and exchanges the heat with the water to produce steam or heated water depending on the application.
How many types of exchangers are there?
The three most common types of shell-and-tube exchangers are (1) fixed tubesheet design, (2) U-tube design, and (3) floating-head type.
What 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.