This preview shows page 1. Sign up to view the full content.
Chapter 1
Basics of Heat Transfer
134
A hot copper block is dropped into water in an insulated tank. The final equilibrium temperature of
the tank is to be determined.
Assumptions
1
Both the water and the copper block are incompressible substances with constant specific
heats at room temperature.
2
The system is stationary and thus the kinetic and potential energy changes are
zero,
ΔΔ
KE
PE
==
0 and
E
U
=
.
3
The system is wellinsulated and thus there is no heat transfer.
Properties
The specific heats of water and the copper block at room temperature are
C
p, water
= 4.18
kJ/kg·
°
C and
C
p, Cu
= 0.386 kJ/kg·
°
C (Tables A3 and A9).
Analysis
We observe
that the volume of a rigid tank is constant We take the entire contents of the tank,
water + copper block, as the
system
. This is a
closed system
since no mass crosses the system boundary
during the process. The energy balance on the system can be expressed as
EE
E
U
in
out
−=
=
Net energy transfer
by heat, work, and mass
system
Change in internal, kinetic,
potential, etc. energies
This is the end of the preview. Sign up
to
access the rest of the document.
 Fall '10
 Dr.DanielArenas
 Thermodynamics, Mass, Heat

Click to edit the document details