An open feed water heater operates at steady state with liquid water entering inlet 1 at 10 bar, 50 degree c and a mass flow- rate of 60 kg/s. a separate stream of steam enters inlet 2 at 10 bar and 200 degree c. saturated liquid at 10 bar exits the feed water heater at exit 3. ignoring heat transfer with the surroundings and neglecting kinetic and potential energy effects, determine the mass flow rate, in kg/s, of the steam at inlet 2.

16.46 kg/s

Explanation:

We solve this by writing an energy balance around the open feed water heater:

E,in=E,out

We know that heat transfer to surroundings and kinetic and potential energy are zero.

We can use the thermodynamic tables for saturaed liquid and steam to solve for the enthalpies.

For inlet 1:

50°C, 10 bar

For inlet 2:

steam, 10 bar, 200°C

For outlet 3:

Saturated liquid at 10 bar

We can also perform a mass balance:

We can solve the energy balance:

Solve for m₂

the equation above shows how temperature f, measured in degrees fahrenheit, relates to a temperature c, measured in degrees celsius. based on the equation, which of the following must be true?

a temperature increase of 1 degree fahrenheit is equivalent to a temperature increase of

5

9

degree celsius.

a temperature increase of 1 degree celsius is equivalent to a temperature increase of 1.8 degrees fahrenheit.

a temperature increase of

5

9

degree fahrenheit is equivalent to a temperature increase of 1 degree celsius.

a) i only

b) ii only

c) iii only

d) i and ii only

answer:

yes

explanation: