Table of Contents

## How do you size an air to air heat exchanger?

An air to air heat exchanger’s capacity is specified in Watts per degree Fahrenheit (and also Centigrade) temperature difference. For a rough estimate, calculate the heat load of the enclosure in Watts and then divide the heat load by the capacity of your air to air heat exchanger.

**How do you calculate heat exchanger?**

The main basic Heat Exchanger equation is:

- Q = U x A x ΔTm = The log mean temperature difference ΔTm is:
- ΔTm = (T1 – t2) – (T2 – t1)
- = °F. Where:
- T1 = Inlet tube side fluid temperature; t2 = Outlet shell side fluid temperature;
- ln (T1 – t2) (T2 – t1)

### How do you calculate the heat transfer coefficient of liquid?

As the mass flow may be calculated with dm = dv x ρ (volume flow times density) we will get the “qualitative” Heat transfer coefficient αm . Using: T2, T1 the inlet and outlet temperature of the fluids and the volume flow. The heat loss is also taken as constant.

**How efficient are air to heat exchangers?**

The longer the air runs in the unit, the greater the heat exchange. The percentage of heat recovery is the efficiency of the unit. Efficiencies usually range around 80 percent.

## What is the formula for BTUs?

BTU = Flow Rate In GPM (of water) x (Temperature Leaving Process – Temperature Entering Process) x 500.4*Formula changes with fluids others than straight water.

**How many BTU does it take to heat a gallon of water?**

8.33 BTU

One BTU is the amount of heat energy required to raise one pound of water by 1ºF. Water weighs 8.33 pounds per gallon so we can calculate that one gallon of water requires 8.33 BTU to raise the temperature 1ºF.

### How do you calculate heat transfer coefficient experimentally?

For determining the heat transfer coefficient the chip is replaced with a heating coil. The power input to the heating coil is obtained by measuring the input voltage and current. Temperature measurement for varying heat inputs is done using RTD thermocouples.

**How do you calculate the overall heat transfer coefficient of a plate heat exchanger?**

Calculation method

- Heat load, Theta and LMTD calculation. Where: P = heat load (btu/h) m = mass flow rate (lb/h)
- Heat transfer coefficient and design margin. The total overall heat transfer coefficient k is defined as: α1 = The heat transfer coefficient between the warm medium and the heat transfer surface (btu/ft2 h °F)

## Should I run my air exchanger in the winter?

Optimize air circulation and replace natural ventilation Air exchangers should be run at all time, summer and winter. Depending on the size of your home, energy-efficient air exchangers can cycle through all the air in your home in just a few hours.

**Will an air exchanger remove humidity?**

In summer, the heat exchanger can cool and, in some cases, dehumidify the hot outside air passing through it and into the house for ventilation. The air-to-air heat exchanger removes the excess humidity and flushes out odors and pollutants generated indoors.