Titanic's Reciprocating Engine Room was located between the Turbine Room and Boiler Room 1. It contained the two reciprocating engines, the feedwater heaters, the ship’s refrigeration plant, and other auxiliary equipment.
There are no images of the Reciprocating Engine Room, but the 1997 Film Titanic gives a good example of how the room looked like and how it worked. Titanic's top speed was 24 knots which was 27 mph. At the time of the collision, Titanic was sailing at 21 knots, even though popular belief claims she was at top speed. These engines were used to power the starboard and port wing propellers.
The Reciprocating Engine Room was compromised when the double bottom broke up and took the forward cylinders with them.
Two large Refrigeration Engines were responsible for running the massive refrigeration complex on the Orlop and G-Deck, as well as keeping the drinking water throughout the ship's cabins and pantries cold. These Engines would need to be kept running at all times while at sea so as to ensure that the proper amount of refrigeration was generated to maintain some of the more delicate items of Titanic's refrigerated holds, such as ice makers and ice cream.
During the sinking, it is very likely that these engines were shut down in the efforts to reduce steam usage by non critical systems on board. It is unlikely that enough time would have passed for passengers to ever notice the effects of this shutdown during the sinking. however, as most of the ship's supply of chilled water and ice would have been cold enough to remain chilled for several hours-longer than the time it took for the ship to sink.