Armando Colimodio
Person #: 2923-7373
Parking Lanes Defroster for
Outdoor Parking Lots during the winter
Abstract:
Understanding the heat transfer interaction between snow
and an asphalt surface is of paramount practical significance. In this paper,
the heat transfer process is investigated utilizing a defroster grid located in
the paint of the parking lanes of a parking lot. The objective of this project
is to melt the snow that covers the lanes to know exactly where to park. The
system use solar energy to produce the voltage required to create the heat
produced by the resistance. The system utilizes solar panels that charge the
batteries to keep the energy for the defroster grid. The result was a program
that calculates the energy required to melt the snow of a specific size parking
lot. For 100 parking spaces the energy required is equal of 4 batteries and 4
solar panels with a total 984.23 amps per hour (0.2734 Amps per second).
Introduction:
A parking lot will have the capability to automatically turn (on or off) the defroster located in the painted lanes that mark the car space when required by transducers (which measure outside versus floor temperature). To support this, a special cooper defroster grid will be design. The current grid design uses five vertical wires 3m long, separated by 0.025m horizontal wires as shown in diagram below. We are going to calculate how much energy a specific parking lot will required to melt the snow over the parking lanes. This parking lot will be powered by the batteries necessary and the batteries will be charge by solar panels.
The voltage source (circle at bottom) can vary dynamically (under control by the transducer) from 10 to 12V.
1-
Solar panel.
2-
Switch and
thermostat.
3-
4-
Cooper Defroster
grid.
Analysis:
A cooper
resistor was used; the heating pad wattage (input) is the product of volts time
amps. The convected heat by the flowing air is computed by 
where Q
loss is the rate of heat transfer, in watts, off the back surface of the
heater. This heat loss was quantified based on the temperature of the back
surface of the heater and the temperature of the outer surface (snow or ice) of
the insulation pad. Q rad is the radiation heat transfer exchanged
between the inner surface of asphalt and the surroundings.
. We used cooper wire with a resistivity of
1.72 x 10^-8 ohms per meter, conductivity of 5.81 X 10^7(ohms per meter)^-1 and
Temperature coefficient of 0.0039 (Celsius)^-1.
To
calculate the amount of energy required to melt the snow in the parking lots,
we first need to calculated the temperature to melt the snow or ice that we
already know to be more than 0 degrees Celsius or more than 32 F. With the
temperature we can calculate the cross area of the wire need to obtain the
resistance of the cooper. Then, with the resistance we can calculate the
required voltage.
Assumptions:
-One
dimensional, steady state conditions.
-Constant
resistance.
-
Negligible radiation exchange with surroundings.
-Cooper
constant properties.
- High ambient temperature lowers generator output voltage because the battery charges easily when warm. If the charging voltage did not decrease, the battery would be severely damaged from overcharging. The only reason the charging voltage changes with temperature is to meet the battery's charging needs, which changes with temperature changes.
- The opposite applies at low ambient temperature. Batteries do not charge very well when cold so the charging voltage rises in cold weather to ensure the battery charges properly.
- High electrical load lowers generator output voltage. It's just like placing a load on a battery and watching battery voltage decrease. If the electrical load is very heavy, charging voltage may be lower than normal and undercharge the battery.
- High electrical load increases generator output current and generator heat increases.
- Low electrical load allows generator output voltage to rise to a set point determined by the voltage regulator.
- The two
factors that determine battery charging current are battery state of charge and internal battery resistance.
Both increase as the battery charges, which lower
the charging current through the battery.
Symbols and Units:
Discussions of the
Results:
In the project we
calculate the energy required to melt the snow that covers the lanes of a
parking lot to know exactly where to park. The system used solar energy to
produce the voltage required to create the heat produced by the resistance. The
system will use solar panels to charge the batteries that keep the energy for
the defroster grid. The result was a program that calculates the specific energy
required to melt the snow of a specific size parking lot. For 100 parking
spaces the energy required is equal to 4 batteries of 257 Amps per hour and 4
solar panels of 160 watts 4.55 amps. The total current needed was 984.23 amps
per hour that is 0.2734 Amps per second.
The energy dissipated to the
defroster grid will be for 60 seconds every 5 minutes, with this time we
optimize the consume of energy reducing the quantity of supplies needed and giving chance to the charging system to
do his job.
Conclusion:
We can say that is possible to fix the problem when snow covers the lanes in the parking lots and cars start to park randomly. We found that we can use free energy using solar energy and storage it in batteries. With the creation of the program calculate the basics supplies needed for different sizes of parking lots.
References:
-Fishbane Gasiorowicz Thornton, Physics for Scientists and Engineers Second Edition Volume II.
-Yunus A, Cendel. Thermodynamics. An Engineering approach Fourth Edition
Graw Hill.
-Incropera, Frank P. Introduction to Heat Transfer. Fourth Edition.John Wiley Sons.
Figures:
Solar
Panels