solution#5 - 5-85 Ethylene glycol is cooled by water in a...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
5-85 Ethylene glycol is cooled by water in a heat exchanger. The rate of heat transfer in the heat exchanger and the mass flow rate of water are to be determined. Assumptions 1 Steady operating conditions exist. 2 The heat exchanger is well-insulated so that heat loss to the surroundings is negligible and thus heat transfer from the hot fluid is equal to the heat transfer to the cold fluid. 3 Changes in the kinetic and potential energies of fluid streams are negligible. 4 Fluid properties are constant. Properties The specific heats of water and ethylene glycol are given to be 4.18 and 2.56 kJ/kg. ° C, respectively. Analysis ( a ) We take the ethylene glycol tubes as the system, which is a control volume. The energy balance for this steady-flow system can be expressed in the rate form as Then the rate of heat transfer becomes ( b ) The rate of heat transfer from glycol must be equal to the rate of heat transfer to the water. Then, 5-96 Two streams of water are mixed in an insulated chamber. The temperature of the exit stream is to be determined. Assumptions 1 This is a steady-flow process since there is no change with time. 2 Kinetic and potential energy changes are negligible. 3 There are no work interactions. 4 The device is adiabatic and thus heat transfer is negligible. Properties From the steam tables (Table A-4), h 1 2245 h f @ 90 ° C = 377.04 kJ/kg h 2 2245 h f @ 50 ° C = 209.34 kJ/kg Analysis We take the mixing chamber as the system, which is a control volume since
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

Page1 / 4

solution#5 - 5-85 Ethylene glycol is cooled by water in a...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online