A Thomas flowmeter is a device in which heat is transferred at a measured rate from an electric coil to a flowing fluid, and the flow rate of the stream is calculated from the measured increase of the fluid temperature. Suppose a device of this sort is inserted in a stream of nitrogen, the current through the heating coil is adjusted until the wattmeter reads 1.25 kW, and the stream temperature goes from 30°C and 110 kPa before the heater to 34°C and 110 kPa after the heater.
(a) If the specific enthalpy of nitrogen is given by the formula H^ ( kJ / kg ) = 1.04 [ T ( ° C ) − 25 ] Hˆ(kJ/kg) =1.04[T(°C)−25], what is the volumetric flow rate of the gas (L/s) upstream of the heater (i. e., at 30°C and 110 kPa)?