Assignment No. 2

Submitted by: Group A : 10CH10003 – ANAMIKA CHOWDHURY 10CH10008 – ANKUR ABHINAV 10CH10038 – ROHAN ROY

Problem Statement

For a heat exchanger operating in steady state, take the following variables as input:

Hot and cold stream inlet temperatures, specific heats, mass flow rates and U and A value of the heat exchanger

Calculate outlet temperature of hot and cold streams using wegstein convergence method

Equations :

Mh*Cph*(Thi - Tho) = Mc*Cpc*(Tco - Tci) (- Eq.1)

Mh*Cph*(Thi - Tho) = U*A*LMTD (- Eq.2)

Algorithm 1. Take an initial guess value of Tho2. Using this value calculate the Tco.The heat balance equation is considered and

corresponding Tco (temperature of outgoing cold fluid) is obtained.Equation: m1*Cp1*(Thi- Tho) = m2*Cp2*(Tco-Tci)=Qm1: mass flow rate of hot fluid m2: mass flow rate of cold fluidCp1: specific heat capacity of hot fluid Cp2: specific heat capacity of cold fluidThi: Incoming hot fluid temperature Tci: Incoming cold fluid temperature

3. Using Eq.2; again calculate Tho4. Using above two calculate Tho values and wegstein convergence method; calculate the

exact value of Tho

Robustness in programThere can be following input errors in the program and hence necessary actions have also been formulated.1) The Tci must always be less than Thi. 2) The guess value of Tho should be less than Thi, heat transfer is between a hot and a cold fluid.

Validation of the program from the example problem of book

READING:m1= 1260 kg/hr Thi=100 ◦Cm2= 1260 kg/hr Tci= 30 ◦CCp1= 1 kJ/kg◦C Tho (initial guess) = 35 ◦CCp2= 1.5 kJ/kg◦C U =200 W/ m2◦C A= 1 m2

RESULTS:Tho= 90.24 ◦CTco= 36.51 ◦C