SI: A single device can heat fluids without requiring an electrical element. S6 : Because there is no electrical element, there is no risk of fire, so the system is suitable for dangerous environments. P : A heat exchanger transfers heat from the central cavity to an air heater, a water heater or an industrial processor. Q : It has a container like the crank case of a car’s engine, which contains the fluid to be heated. R : Compression and friction at the nozzles heat the fluid so that the temperature in the central cavity rises steadily. S : A motor and pulley inside the container turn a rotor wheel, which in turn forces the fluid again and again through narrow nozzles into a central cavity. The proper sequence should be
- AR P S Q
- BS P Q R
- CQ S R P
- DS R P Q
Explanation
Q describes the apparatus first: a container like a car's crank case holding the fluid. S explains the mechanism: motor and pulley turn a rotor wheel, forcing fluid through nozzles into a central cavity. R gives the heating: compression and friction raise the temperature steadily. P shows the output: a heat exchanger transfers the heat to an air/water heater or processor. S6 concludes: with no electrical element there is no fire risk. Hence QSRP, i.e. option C.