ICAR AIEEA PG Agriculture Engineering 14 July 2023 (Shift 1) Paper

The compressor draws low-pressure, low-temperature refrigerant vapor from the evaporator and isentropically compresses it, which circulates the refrigerant (A), raises its pressure to condenser pressure (B), and significantly raises its temperature above condensing temperature (C) (superheated vapor). The expansion valve reduces temperature/pressure (D). Hence (A), (B), and (C) are the functions. Option analysis: (A) Includes incorrect statement (D). (B) Omits temperature rise (C). (C) (A), (B) and (C) only is the correct answer. (D) Omits circulation function (A).

The $F$-value (thermal death time or process lethality) is the total heating time in minutes at a specified reference temperature required to achieve a specified overall reduction ratio (such as $12D$ reduction) in a target microbial population. The $D$-value is specifically the time for a single decimal ($90\%$) reduction. Option analysis: (A) $D$-value is for one log ($90\%$) reduction only. (B) $F$-value represents the total process time to achieve a specified overall reduction ratio. (C) $Z$-value is the temperature increase required to change $D$-value by a factor of $10$. (D) $Q_{10}$ is temperature coefficient.

Cyclone separators utilize centrifugal force to separate dust particles ($\gt 10\,\mu\text{m}$) from gas/air streams (A), and hydrocyclones separate solid particulate matter from liquid suspensions (B). Statement (D) is completely false because cyclones are separation devices, not size reduction (grinding) equipment. According to official answer key, option 1 '(A) and (B) only' is the correct answer. Option analysis: (A) (A) and (B) only is the officially designated correct answer. (B) Contains false statement (D). (C) Includes (C) which is demister duty. (D) Contains false statement (D).