FAA Powerplant Written Practice Test

Which type of heat exchanger is used to regulate fuel temperature in turbine engines?

1. Liquid-to-liquid heat exchanger

2. Air-to-liquid heat exchanger

3. Cooling coil heat exchanger

4. Electronic heat exchanger

The correct answer is: Air-to-liquid heat exchanger

The type of heat exchanger used to regulate fuel temperature in turbine engines is the air-to-liquid heat exchanger. This system is designed to ensure that the fuel is kept at an optimal temperature for efficient combustion and performance. In turbine engines, the fuel is circulated through a heat exchanger where it is cooled or warmed by airflow, based on the operational needs and environmental conditions. As the engine operates, the fuel tends to heat up due to the high temperatures in the combustion area. An air-to-liquid heat exchanger utilizes ambient air as a cooling medium, allowing for effective heat transfer. This helps in maintaining the fuel within a specific temperature range, which is vital to prevent issues like fuel vaporization or excessive viscosity, both of which can adversely affect engine performance and reliability. The other types of heat exchangers listed have different functions or are not employed for regulating fuel temperatures in turbine engines specifically. For instance, a liquid-to-liquid heat exchanger might be more suitable for cooling engine oil or other liquids, while cooling coils and electronic heat exchangers typically serve different applications in thermal management systems.