Cross Flow Heat Exchanger Calculation

Cross Flow Effectiveness Formula:

\[ \text{Effectiveness} = 1 - \frac{\exp(-NTU (1 - C))}{1 - C \exp(-NTU (1 - C))} \]

Effectiveness:

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1. What is Cross Flow Effectiveness?

Cross flow effectiveness is a measure of heat exchanger performance, representing the ratio of actual heat transfer to maximum possible heat transfer. It quantifies how efficiently a cross flow heat exchanger operates under given conditions.

2. How Does the Calculator Work?

The calculator uses the cross flow effectiveness formula:

\[ \text{Effectiveness} = 1 - \frac{\exp(-NTU (1 - C))}{1 - C \exp(-NTU (1 - C))} \]

Where:

\( NTU \) — Number of Transfer Units (dimensionless)
\( C \) — Capacity ratio (dimensionless)
\( \exp \) — Exponential function

Explanation: The equation calculates the effectiveness based on NTU and capacity ratio, considering the thermal characteristics of cross flow heat exchangers.

3. Importance of Effectiveness Calculation

Details: Effectiveness calculation is crucial for heat exchanger design, performance evaluation, and optimization. It helps engineers determine the efficiency of heat transfer systems and make informed design decisions.

4. Using the Calculator

Tips: Enter NTU (Number of Transfer Units) and capacity ratio (C) as positive numbers. Both values must be valid (≥0).

5. Frequently Asked Questions (FAQ)

Q1: What is NTU in heat exchangers?
A: NTU (Number of Transfer Units) is a dimensionless parameter that represents the heat transfer size of the exchanger relative to the heat capacity rate of the fluids.

Q2: What does capacity ratio (C) represent?
A: Capacity ratio is the ratio of the minimum to maximum heat capacity rates of the two fluids. It ranges from 0 to 1.

Q3: What are typical effectiveness values?
A: Effectiveness typically ranges from 0 to 1, with higher values indicating better heat exchanger performance. Most practical heat exchangers have effectiveness between 0.5 and 0.9.

Q4: When is this formula applicable?
A: This formula applies to cross flow heat exchangers with both fluids unmixed. Different formulas are used for parallel flow, counterflow, or mixed cross flow configurations.

Q5: What are the limitations of this calculation?
A: This calculation assumes constant fluid properties, negligible heat loss to surroundings, and steady-state operation. It may not be accurate for extreme conditions or complex flow arrangements.