Mechanical Engineering - Heat Transfer, Refrigeration and Air Conditioning - Discussion

The correct answer is three heat exchangers.

A bootstrap air cooling system typically consists of:

1. Evaporator (cooler): cools the air
2. Condenser: rejects heat to the atmosphere
3. Reheater (bootstrap heat exchanger): transfers heat from the hot air to the refrigerant, allowing the system to operate at a lower temperature difference

This three-heat-exchanger configuration enables the system to achieve lower temperatures and higher efficiency.

- One heat exchanger: insufficient for a bootstrap system.
- Two heat exchangers: typical for a basic vapour-compression cycle, but not for a bootstrap system.
- Three heat exchangers: correct configuration for a bootstrap air cooling system.
- Four heat exchangers: not necessary for a bootstrap air cooling system.

Bootstrap and bootstrap evaporative system have two heat exchangers.

Air cooler and aftercooler, two HE required.

Once a system has been started by some external power source, the working fluids sustain the process on a self-sustaining basis, such a system is known as a bootstrap system. The bootstrap system used by aircraft is the bootstrap air conditioning system which provides adequate cooling to the cabin and electronic equipment. The bootstrap air conditioning system mainly consists of two units, the cold air unit, and a heat exchanger, both of which are mounted on a common shaft.

So, the heat exchanger should be one.