Heat exchanger problem in Thermodynamics.

[HollowScar]

Hi!

I get the basics now, but this problem has got me stumped. I am trying to figure out where to start.

Homework Statement

In a heat exchanger, cold water flows through the tubes of the exchanger. It enters at 5.5°C, and leaves at 65°C. In the shell of the exchanger steam is being condensed. The steam enters at atmospheric pressure and 100°C, and the condensate that is formed leaves the exchanger before it can be cooled. The flow rate of the steam is 15.0 kg/s. What is the cooling flow rate?

Homework Equations

Oil flows through a heat exchanger at a flow rate of 125 L/min. It enters at 20°C and leaves at 75°C. The oil has a specific heat of 2.84 kJ/kgK and a relative density of 0.8. The oil is being heated by steam. The steam enters the heat exchanger at 100°C and the condensate formed leaves the heat exchanger at 85°C. Calculate the mass flow rate of the steam.

The Attempt at a Solution

First thing we know is that cool water flows through the tube, and exits as warm water. In the shell, steam is being condensed. So basically water turns into steam.

Q (cool water absorbing heat) becomes hot water.
Q = mcΔt + mLv + mcΔt (water becomes steam)

The idea is solid, but I am not sure how I take the above, and find the flow rate. For all I know, those two are different categories.

Thank you for your help. I am this close to finishing up the course, so stumbling at this point does hurt, but the help which I receive will mean a lot to me.

 

[AvroArrow]

To solve this problem, you will need to use the equation of heat energy transfer, which is given by: Q = mcΔT. This equation states that the heat energy transferred (Q) is equal to the mass (m) of a substance multiplied by its specific heat capacity (c) and the change in temperature (ΔT). In your case, the cold water is absorbing heat from the steam, so you can calculate the flow rate of the cooling water using this equation. You know the mass flow rate of the steam (15.0 kg/s), the specific heat capacity of the water (4.18 kJ/kgK), the temperature difference between the inlet and outlet temperatures of the water (5.5°C - 65°C), and the heat energy transferred (Q). You can rearrange the equation to solve for m, the mass flow rate of the cooling water, which you can then use to calculate the flow rate in L/min.