Quick Answer: Why Is A Countercurrent Heat Exchanger More Efficient?

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..

Does turbulence increase heat transfer?

A turbulent flow increases the amount of air resistance and noise; however, a turbulent flow also accelerates heat conduction and thermal mixing.

Why is there a pressure drop across a heat exchanger?

Pressure drop is a major constraint in thermal design of shell and tube heat exchangers. … Overall heat transfer coefficient can be maximized by maximizing shell side and tube side flow velocities, which, in turn, is governed by the allowable pressure drop as higher velocity means higher pressure drop.

Why is countercurrent flow important?

Fish gills use a design called ‘countercurrent oxygen exchange’ to maximize the amount of oxygen that their blood can pick up. They achieve this by maximizing the amount of time their blood is exposed to water that has a higher oxygen level, even as the blood takes on more oxygen.

Which type of heat exchanger is more efficient?

In counter-flow heat exchangers the fluids enter the exchanger from opposite ends. The counter current design is the most efficient, in that it can transfer the most heat from the heat (transfer) medium per unit mass due to the fact that the average temperature difference along any unit length is higher.

How does countercurrent heat exchanger conserve heat?

The warm arterial blood transfers most of its heat to the cool venous blood now coming in from the outside. This conserves heat by recirculating it back to the body core. Since the arteries give up a good deal of their heat in this exchange, there is less heat lost through convection at the periphery surface.

How do I choose a heat exchanger?

The following criteria can help in selecting the type of heat exchanger best suited for a given process:Application (i.e. sensible vapor or liquid, condensing or boiling)Operating pressures & temperatures (including startup, shutdown, normal & process upset conditions)More items…

What is the best material for a heat exchanger?

Thermal Efficiency Based on thermal modeling comparisons using HTRI software, copper and copper/nickel are typically the most conductive material available for exchanger tubes. Carbon steel, stainless steel and higher alloys are slightly less efficient, but all perform similarly.

Does heat transfer increase with flow rate?

On the other hand, an increase in the heat transfer coefficient is observed if the area is maintained constant. Doubling the mass flow rate will result in a 92% increase in the heat transfer coefficient. However, there is a concomitant increase in the pressure drop, proportional to the mass flow rate raised to 0.95.

Why is one way flow an advantage to fish?

2. Because water is more vicious than air, it takes more energy to ventilate and swim through it. This causes an increase in demand for oxygen, and therefore fish have a continuous unidirectional flow of water over their gills for maximum diffusion efficiency.

Why is it important that gills have lots of surface area?

Water flows over the gills so oxygen is removed and enters the blood. The surface area of the gill filaments is an important factor in gas exchange. Water contains much less oxygen compared to air; therefore fish must have an organ (gills) with a large surface area to get enough oxygen from the water to survive.

What affects heat exchanger efficiency?

Heat exchanger efficiency is highly affected by the velocity of the operating fluid so it is recommended that the flow rate should be increased from time to time. The increased turbulence works to retard fouling tendencies that otherwise impact heat exchanger performance and impede the flow of fluids.