Programmed Solutions - HP -10C Owner's Handbook Manual

q is the heat loss from the water
heater (Btu per hour).
h is the heat-transfer coefficient.
A is the total surface area of the
cylinder.
T is the temperature difference
between the
surrounding air.
Example: Assume you have a 52-gallon
cylindrical water heater and you wish to
determine how much energy is being lost because of poor insulation. In initial
measurements, you found an average temperature difference between the heater
surface and surrounding air of 15° F. The surface area of the tank is 30 square
feet and the heat transfer coefficient is approximately 0.47. To calculate the heat
loss of the water heater, simply press the following keys in order.
Keystrokes
15v
30
*
.47
*

Programmed Solutions

The heat loss for the water heater in the preceding example was calculated for a
15° temperature difference. But suppose you want to calculate the heat loss for
several temperature differences? You could perform each heat loss calculation
manually. However, an easier and faster method is to write a program that will
calculate the heat loss for any temperature difference.
Writing the Program. The program is the same series of keystrokes you
executed to solve the problem manually.
Loading the Program. To load the instructions of the program into the HP-10C
press the following keys in order. The calculator records (remembers) the
instructions as you key them in. (The display gives you information you will
find useful later, but which you can ignore for now.)
Your HP-10C: A Problem Solver
cylinder and
Display
15.0000
30.
450.0000
0.47
211.5000
the
Input temperature
difference (T) and area
of water heater {A).
Calculates A × T.
Heat-transfer coefficient
(h).
Heat loss in Btu per hour
(h × AT).
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