# Quick Answer: What Happens When Lmtd Is Zero?

## What is effectiveness of fin?

Effectiveness of fin (εfin): It is defined as the ratio of the actual heat transfer that takes place from the fin to the heat that would be dissipated from the same surface area without fin..

## Which of the following is not associated with a heat exchanger?

3. Which of the following is not associated with a heat exchanger? Explanation: The correction factor i.e. Mc Adam’s is associated with laminar film condensation on a vertical plate.

## What is effectiveness NTU method?

Effectiveness-NTU Method LMTD method is useful for determining the overall heat transfer coefficient U based on experimental values of the inlet and outlet temperatures and the fluid flow rates. However, this method is not very convenient for prediction of outlet temperatures if the inlet temperatures and U are known.

## How do you measure turbidity in water?

The water collected in a bottle will be used to find out the turbidity, which is measured by shining a light through the water and is reported in nephelometric turbidity units (NTU). During periods of low flow (base flow), many rivers are a clear green color, and turbidities are low, usually less than 10 NTU.

## What NTU means?

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 do small and large NTU values tell about a heat transfer system?

Number of Transfer Units (NTU) The NTU is a function of the Effectiveness and HCRR established by the process temperatures and flow rates and is indicative of the size of the heat exchanger needed. The greater the value of NTU, the larger the heat transfer surface area (A) required to meet the process conditions.

## Which one is having the lowest value of fouling factor?

Which one is having the lowest value of fouling factor? Explanation: Fouling factor for non-oil bearing system is 0.0001 while that of fuel gases, oil bearing system and engine exhaust are 0.0010, 0.0002 and 0.002 respectively.

## What is fouling factor?

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. …

## Why is lmtd needed?

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 use of the LMTD arises, straightforwardly, from the analysis of a heat exchanger with constant flow rate and fluid thermal properties.

## Can log mean temperature difference be negative?

According to the definition modeled above, LMTD cannot be negative.

## How do you calculate lmtd?

by definition given above, LMTD for counter current flow = (60-50) / ln(60/50) = 10 / 0.1823 = 54.850C. For co-current heat exchanger, ΔT1 = TH1 – TC1 = 100 – 30 = 700C (At first end hot and cold fluids enter the heat exchanger.) (At the other end hot and cold fluids exit the heat exchanger.)