Question

QUESTION 4 A surface condenser operates under the following conditions: Wet-steam flow rate = 3 600 kg/hr Mass of cooling water = 18 kg/s Operating pressure = 10 kPa Dryness factor = 0,82 Condensate temperature = 29 °* . . Cooling water inlet temperature = 18 °C Specific heat capacity of water = 4,187 kJ/kg. °C Calculate the outlet temperature of cooling water in °C.​

Answer 1

To calculate the outlet temperature of the cooling water, we can use the energy balance equation for a surface condenser:

Q_condensed + Q_cooled = Q_input

Where:

Q_condensed = m_dot * (h_fg)

Q_cooled = m_dot_water * C_water * (T_outlet - T_inlet)

Q_input = m_dot * h_in

Given:

Wet-steam flow rate (m_dot) = 3600 kg/hr = 1 kg/s

Mass of cooling water (m_dot_water) = 18 kg/s

Operating pressure = 10 kPa

Dryness factor = 0.82

Condensate temperature = 29 °C

Cooling water inlet temperature (T_inlet) = 18 °C

Specific heat capacity of water (C_water) = 4.187 kJ/kg.°C

First, calculate the enthalpy of the inlet condition of the steam (h_in):

Using steam tables at 10 kPa and dryness factor 0.82, find the enthalpy of saturated vapor (h_fg) and the enthalpy of saturated liquid (h_f). Then:

h_in = (1 - dryness factor) * h_f + dryness factor * h_fg

Next, rearrange the energy balance equation to solve for the outlet temperature of cooling water (T_outlet):

T_outlet = (Q_input - Q_condensed) / (m_dot_water * C_water) + T_inlet

Substitute the values into the equations, calculate h_in, h_condensed, and T_outlet to get the outlet temperature of cooling water.

Remember to convert units consistently throughout the calculations.

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