An adiabatic heat exchanger is used to heat cold water at 15°C entering at the rate of 10 kg/sec by hot air at 90°C entering at the rate of 10 kg/sec. if the exit temperature of cold water is 29°C then what will be the temperature of hot air at the exit. Cp for air = 1.008 KJ/Kg. Cp for water = 4.18 KJ/Kg: 

This question was previously asked in
SSC JE ME Previous Paper 8 (Held on: 27 October 2020 Evening)
View all SSC JE ME Papers >
  1. 26.54°C
  2. 31.88°C
  3. 58.65°C
  4. 89.12°C

Answer (Detailed Solution Below)

Option 2 : 31.88°C
Free
RRB JE CBT I Full Test - 23
14.2 K Users
100 Questions 100 Marks 90 Mins

Detailed Solution

Download Solution PDF

Concept:

By usimg equilibrium of heat exchanger, we know that,

Heat loss by Hot air = Heat gain by cold water

\({\left( {m{C_p}\Delta T} \right)_{Air}} = {\left( {m{C_p}\Delta T} \right)_{water}}\)

Calculation:

Given:

For air:

Ti = 90°C, To = 20°C, m = 10 kg/s, Cp = 1.008 kJ/kgK

For water:

Ti = 15°C, To = ?,  m = 10 kg/s, Cp = 4.18 kJ/kgK

⇒ 10 × 1.008 × (90 – Tf) = 10 × 4.18 × (29 – 15)

⇒ Tf = 31.6° C
Latest SSC JE ME Updates

Last updated on May 28, 2025

-> SSC JE ME Notification 2025 will be released on June 30. 

-> The SSC JE Mechanical engineering application form will be available from June 30 to July 21. 

-> SSC JE 2025 CBT 1 exam for Mechanical Engineering will be conducted from October 2 to 31. 

-> SSC JE exam to recruit Junior Engineers in different disciplines under various departments of the Central Government.

-> The selection process of the candidates for the SSC Junior Engineer post consists of Paper I, Paper II, Document Verification, and Medical Examination.

-> Candidates who will get selected will get a salary range between Rs. 35,400/- to Rs. 1,12,400/-.

-> Candidates must refer to the SSC JE Previous Year Papers and SSC JE Civil Mock Test, SSC JE Electrical Mock Test, and SSC JE Mechanical Mock Test to understand the type of questions coming in the examination.

Get Free Access Now
Hot Links: teen patti - 3patti cards game downloadable content teen patti download apk teen patti plus teen patti all real teen patti