Out of the following devices, in which equipment two heat exchangers are used instead of one?

Correct option is C

In boilers, two heat exchangers are used: the economizer and the condenser. The economizer absorbs heat from the exhaust gases to preheat the water before it enters the boiler, improving efficiency. The condenser is used in the process to cool down the steam after it has been used to produce power, often in a steam turbine system, and convert it back into water. This dual heat exchange helps in increasing the overall efficiency of the system.
Information Booster: In a boiler system, two distinct heat exchangers help in enhancing the overall energy efficiency:
1. Economizer: It is used to preheat the feedwater using the waste heat from the exhaust gases. This reduces the amount of fuel needed to generate steam.
2. Condenser: After steam has been used in turbines, it needs to be condensed back into water for reuse. The condenser, typically in a closed-loop cooling system, helps to release the heat to a cooling medium, such as water or air.
Additional Knowledge:
· Television: Televisions do not typically use heat exchangers. They may have passive cooling methods like heat sinks but no specific heat exchangers.
· Refrigerator: Refrigerators have two heat exchangers, but they function differently from a boiler system.
· Oven: Ovens typically use one heat source to heat the air inside, and therefore only require a single heat exchanger.