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# How do you calculate the effectiveness of a heat exchanger?

## How do you calculate the effectiveness of a heat exchanger?

Fig. The effectiveness (ϵ) of a heat exchanger is defined as the ratio of the actual heat transfer to the maximum possible heat transfer. Qmax is the minimum of these two values i. e.

What is e NTU?

The E-NTU model defines the heat transfer rate between fluids 1 and 2 in terms of an effectiveness parameter ε: Q 1 = − Q 2 = ϵ Q M a x , 0 < ε < 1 , QMax is the maximum possible heat transfer rate between fluid 1 and fluid 2 at a given set of operating conditions. ε is the effectiveness parameter.

What is effectiveness of a heat exchanger?

Heat exchanger effectiveness is defined as the ratio of the actual amount of heat transferred to the maximum possible amount of heat that could be transferred with an infinite area. Two common methods are used to calculate the effectiveness, equations and graphical.

### How is NTU calculated in heat exchanger?

The number of transfer units (NTU = UA/(mcp)) itself is a combination of overall heat transfer coefficients, transfer area, fluid flow rate and heat capacity.

What is the maximum value for heat exchanger effectiveness?

Another approach introduce the definition of heat exchanger effectiveness (Є), which is a dimensionless with ranging between 0 to1. Where, qmax is the maximum possible heat transfer for the exchanger.

Can effectiveness of heat exchanger be greater than 1?

The ratio of actual heat transfer rate to the maximum possible heat transfer rate is known as the effectiveness of heat exchanger. The heat transfer effectiveness is always less than the actual heat transfer.

#### Why LMTD is used in heat exchanger?

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.

Why we use NTU method?

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 most efficient heat 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 HTU and NTU?

The number of transfer units (NTU) required is a measure of the difficulty of the separation. The height of a transfer unit (HTU) is a measure of the separation effectiveness of the particular packings for a particular separation process.

What is LMTD formula?

Log Mean Temperature Difference (LMTD) is an indicator of the average temperature difference between the hot and cold fluids in a heat exchanger. It is calculated using the following equation – ΔT1 → the temperature difference between hot and cold fluids at one end of the heat exchanger.

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 information is needed to size a heat exchanger?

The minimum information needed to size the heat exchanger for both the hot and cold sides are: fluid names, flow rates, inlet temperature, outlet temperature, operating pressures and maximum pressure drop allowed across the unit.

What is the equation for heat conduction?

The law of heat conduction is also known as Fourier ’s law. Fourier’s law states that. “the time rate of heat transfer through a material is proportional to the negative gradient in the temperature and to the area.”. Fourier’s equation of heat conduction: Q = -kA(dT/dx)

What is the process of a heat exchanger?

It works by burning natural gas , making a line or grid of hot gas jets that fire upward over water flowing through a network of pipes. As the water pumps through the pipes, it absorbs the heat energy and heats up. This arrangement is what we mean by a heat exchanger: the gas jets cool down and the water heats up.