Q1: Tubes are held between top and bottom tube sheets in Calenderia type evaporator by keeping

ANS:A - both the tube sheets fixed.

In a Calandria type evaporator, the tubes are held between the top and bottom tube sheets by keeping the top tube sheet fixed and the bottom tube sheet floating. This configuration allows for thermal expansion and contraction of the tubes without exerting excessive stress on the tube sheets. As the tubes heat up during operation, they expand, and the bottom tube sheet, being floating, can move to accommodate this expansion while maintaining a secure connection between the tubes and the tube sheets. Conversely, as the tubes cool down after operation, they contract, and the floating bottom tube sheet can adjust accordingly to prevent damage to the tubes or tube sheets. Therefore, the correct option is: the top tube sheet fixed and the bottom tube-sheet floating.