Advanced Heat Transfer: Heat Exchangers

Explain heat exchangers by relating heat transfer to hot and cold fluid mass flow rate and temperature changes, assuming no heat loss, and defining the mean temperature difference.

Apply the logarithmic mean temperature difference method to a parallel-flow heat exchanger, derive ΔT_lm, and express heat transfer as Q = U A ΔT_lm using inlet and outlet temperatures.

Study counter-flow heat exchangers, their temperature distribution, and the log mean temperature difference. Compare the log mean temperature difference with parallel flow and note condensers and boilers as special cases.

Investigate special operating conditions in a counterflow heat exchanger, derive the log mean temperature difference, and examine linear temperature distributions for hot and cold streams.

Calculate the overall length of a contraflow heat exchanger cooling oil with water. Use mass flow rates, inlet temperatures, and log mean temperature difference to find the heat transfer area.

Analyzes a plate heat exchanger with 60 gaps, calculating the total heat transfer, u value, and log mean temperature difference for oil and water.

Explore how a correction factor f adjusts the log mean temperature difference between cross-flow, multipass, and counterflow heat exchangers, highlighting boiling/condensation cases.

Condense steam at 30 °C in condenser using cooling water from 14 to 22 °C, applying log-mean temperature difference with surface area and coefficient to estimate mass flow.

Analyze a shell-and-tube exchanger transferring glycerin from 20 °C to 50 °C using water at 80 °C, computing U and LMTD with a correction factor and fouling impact on Q.

Compute the overall heat transfer coefficient for a cross-flow heat exchanger car radiator with both fluids unmixed, using inner-tube area, log-mean temperature difference, and a correction factor for counterflow.

This example analyzes a crossflow heat exchanger with mixed steam and unmixed oil streams, computing the surface area around 11 m² using U=275 W/m²K and F≈0.96.

Introduce the effectiveness-NTU method for heat exchangers and distinguish two problem types, solving for area with log mean temperature difference and highlighting NTU as a practical alternative for outlet temperatures.

Define heat capacity rate and effectiveness, relate NTU and capacity ratio, and outline solving type one and type two heat exchanger problems.

Derives the parallel-flow heat exchanger effectiveness–NTU relationship. Links NTU with heat capacity ratio and C_min/C_max to express epsilon.

Explore the effectiveness and NTU relations for heat exchangers using tables A and B, linking effectiveness, AU, the heat capacity ratio, and zero capacity ratio cases with mixed/unmixed flows.

Demonstrates a counterflow heat exchanger heating cold water from 20 to 80 degrees Celsius with hot water at 160 degrees Celsius, applying epsilon-ntu to determine length, 109 meters.

This example analyzes a copper tube heat exchanger transferring heat from hot oil to water, calculating the heat transfer rate and outlet temperatures using NTU and area from charts.

Analyze a large power plant condenser, a shell-and-tube exchanger with 30,000 tubes, to compute the cooling water outlet temperature and required heat-transfer area using NTU and effectiveness.