Consider the system shown below. A steady flow of water enters and leaves the ve
ID: 967561 • Letter: C
Question
Consider the system shown below. A steady flow of water enters and leaves the vessel at a flow rate of 2 kg/min. It is desired to use a resistance heating element to heat the water in the vessel so that the water exits the vessel at 35 degreeC. Water enters the vessel at 25 degreeC and the heat capacity of water is 4.184 kJ/kg degreeC. The exiting water is simply drained from the vessel by installing the outlet tube at the desired liquid level height. Assuming steady state operation, calculate the required heat flow Q_k (in kJ/min) from the heating element (a) Assuming the tank is perfectly insulated from the surroundings. (b) Assuming the tank is not insulated from the surroundings but transfers heat to the surrounding air (at 25 degreeC) with an overall heat transfer coefficient U = 10 kJ/minmiddotm^2middotdegreeC. The heat transfer area is 2 m^2.Explanation / Answer
a ) Required heat flow Qh = [ m x Cp x (Toutlet - Tinlet ) ] / t (min )
= [ 200g x 0.004184 j x ( 308k - 298 k ) ] / 1
= 8.368 J / min.
=83.68 KJ