Q1: More than 1000 tons refrigeration capacity plants are usually of __________ type.

ANS:B - vapour absorption

Vapour absorption refrigeration is a type of refrigeration system that utilizes the absorption principle to achieve cooling. Unlike vapour compression refrigeration systems, which use mechanical compressors to circulate and compress the refrigerant, vapour absorption systems use a combination of heat and chemical processes to achieve the same result. Here's how a typical vapour absorption refrigeration system works:

1. Evaporation: The process begins with the evaporation of a volatile liquid refrigerant (such as ammonia or water) in an evaporator. This evaporation extracts heat from the surroundings, causing the refrigerant to evaporate and absorb thermal energy.
2. Absorption: The evaporated refrigerant vapour is then absorbed by a solution known as the absorbent. The absorbent is typically a liquid with a high affinity for the refrigerant, such as lithium bromide solution. The absorption process occurs in an absorber, where the refrigerant vapour is absorbed into the absorbent solution, forming a concentrated solution.
3. Heat Input: The concentrated absorbent solution, now containing the dissolved refrigerant, is then heated in a generator or desorber. Heat is supplied to the generator, causing the refrigerant to be released from the absorbent solution as a vapour.
4. Desorption: The released refrigerant vapour is then condensed back into a liquid by rejecting heat in a condenser. This condensed liquid refrigerant is then returned to the evaporator to repeat the cycle.
5. Regeneration: Meanwhile, the absorbent solution, now diluted due to the release of refrigerant, is returned to the absorber. The cycle continues as fresh heat is applied to the absorbent solution in the generator, driving the absorption process.

The key principle behind vapour absorption refrigeration is the use of heat, rather than mechanical work, to circulate and compress the refrigerant. This makes absorption refrigeration systems particularly suitable for applications where waste heat or other low-grade heat sources are available, such as industrial processes, solar energy, or waste heat recovery. Vapour absorption refrigeration systems are known for their energy efficiency, quiet operation, and environmental friendliness, as they often use natural refrigerants and do not require the use of mechanical compressors powered by electricity or fossil fuels. These systems are commonly used in large-scale refrigeration applications, such as industrial cooling, commercial air conditioning, and refrigeration of food and beverages.