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Design of “DeIcer” – A Proposal

Author: Chia-Chieh Yu (2004-04-06); recommended: Yeh-Liang Hsu (2004-04-28).

1.         Mission Statement

The purpose of this project is to design a hand-held heating device for car drivers to melt ice in keyholes, frozen doors and windows in winter, by blowing warm air on them. This device is to be used remotely, and should not have any power cable. The heat source should last about 10~20min before recharge. A functional prototype, as well as all necessary design documents, is to be delivered.

2.         Product Architecture

The use of the heating device, which will be called “DeIcer” in this proposal, can be described in the following event sequence:

“Holding the DeIcer to aim at the target, the user triggers the DeIcer through a triggering mechanism. The blower starts to suck in cold air from outside through the air passage, so that the heat source will have enough time to turn the cold air into warm air. The warm air is then blown out on the target. The energy required for the blower and heat source is stored in the energy storage, and all components are packaged in a packaging case.”

According to this event sequence, there are 6 components in this product: triggering mechanism, heat source, energy storage, blower, air passage, and packaging case. Figure 1 shows the interaction between these 6 components.

Figure 1. Interaction between the components

Functions and design needs of the 6 components are listed below:

(1)   Heat source

The heat source provides heat to heat up the cold air. With the energy storage, the heat source should last for 10~20 min before recharge.

(2)   Blower

The blower sucks cold air from outside and blows warm air on the target. The blower should provide a constant airflow and enough flow rate.

(3)   Energy storage

The type of energy storage depends on the type of heat source and blower selected. It should provide enough working energy for 10~20 min before recharge.

(4)   Air passage

The air passage should be properly designed with the heat source, so that the heat source will have enough time to turn the cold air into warm air.

(5)   Triggering mechanism

The triggering mechanism should be easy to use. It simultaneously triggers the heat source and blower. There should be safety devices built in the triggering mechanism, so that the heat source will not be triggered improperly.

(6)   Packaging case

The packaging case should contain the other 5 components mentioned above and hold them in proper positions. The shape of the packaging case should be easy to be held by hands in use. There should be heat insulation so that the user will not be burned by the heat source.

3.         Current Products Review

In this section we first review 4 existing products to help us generate design concepts for DeIcer: a hairdryer, a lighter gun, a mini vacuum device, and a squirt gun.

(1) A Hairdryer

The hairdryer studied here is the smallest hairdryer we can find. Figure 2 shows the size of the hairdryer. Figure 3 shows the heat source of the hairdryer. Heating coils are wrapped around some burning resistant material and spread along the front part of the hairdryer. Figure 4 shows the heat insulation material wrapped around the outside of the heat source to preventfrom burning the user. An electric fan blows outside air through the heat source directly, as shown in Figure 5.

Figure 2. The size of the hairdryer

Figure 3. Heat source of hairdryer

Figure 4. Heat insulation outside the heat source

Figure 5. Blower of the hairdryer

(2) A Lighter Gun

Figure 6 shows the size of a lighter gun. Figure 7 shows its triggering mechanism. The gas is provided by an ordinary cigarette lighter as shown in Figure 7. The right side of the triggering mechanism is a switch that releases gas from the cigarette lighter, and the left side of the triggering mechanism is a gas pipe that connects to the cigarette lighter to transmit gas. Inside the red button of the triggering mechanism, there is an ignition device, which generates an electric arc at the tip of the lighter gun. Figure 8 shows a safety switch that prevents the user to trigger it abnormally. We did a simple experiment and found that an ordinary cigarette lighter (5ml) can last for about 2400sec in the lighter gun.

Figure 6. The size of lighter-gun

Figure 7. Triggering mechanism of the lighter gun

Figure 8. Safety switch

(3) A Mini Vacuum Device

Figure 9 shows the size of a mini vacuum device. As shown in Figure 10, an electric fan sucks airthrough the front hole into thebottom of the mini vacuum device. We did a simple experiment and found that its air flow rate is about 0.5 L/sec. The electric fan is driven by two parallel AA batteries and can last for about 30min.

Figure 9. The size of mini vacuum machine

Figure 10. Air passage ofthe mini vacuum machine

(4) A Squirt Gun

Figure 11 showed the air flow (solid lines) and water flow (dashed lines) in a squirt gun. Figure 12 shows the triggering mechanism of the squirt gun. When the trigger is released, water under high pressure as injected.

Figure 11. Flow passage of squirt gun

Figure 12. Triggering mechanism of squirt gun

4.         Design Concept of DeIcer

From the review in the previous section, we can generate the design concept for DeIcer. Figure 13 showed the layout of DeIcer. The design concepts for the 6 components are discussed below.

Figure 13. DeIcer design layout

(1)   Heat Source

Among the 6 components, heat source is the most critical. We decide to use a design similar to the lighter gun in Figure 6 and 7 as our heat source because it last longer and the energy storage can be easily replaced with an ordinary cigarette lighter.

One important question is, can DeIcer provide an output temperature of between 60-80 degrees C in cold (between minus 5-20 degrees C) circumstances?

Butane (C4H10) is the fuel used in cigarette lighters. Its heat of combustion is 2870kJ/mole. Its molecular weight is 58.12g/mole, and its density is 0.5788g/cc. Therefore, the total heat of combustion of the 5cc butane in an ordinary cigarette lighter is

       

On the other hand, if the air flow rate of DeIcer is 0.5L/sec, and last for 30 min., the total air flow will be 900L. The specific heat for air at 32  is 1.71865, the density of air is 1.164kg/m3. Therefore the total heat required to heat the 900L (0.9m3) air from -20 to 60 (temperature difference 80) is

       

Two numbers are really close and we should use two burners in DeIcer to ensure that there is enough heat. The temperature of the outlet air can be adjusted by turning on only one burner or both burners.

(2)   Blower

The Blower of DeIcer will be an small electric fan similar to the mini vacuum device shown in Figure 10.

(3)   Air Passage

The design concept of the heat source discussed above is a point heat source. The major design task here is how to extend the heat source along the air passage. The air passage has to be carefully designed along with the blower, so that DeIcer can provide a constant and concentrated air flow.

(4)   Energy Storage

The energy storage for the heat source will be ordinary cigarette lighters, and the energy storage for the blower will be batteries. The melting point of butane used in ordinary cigarette lighters is –138.3, and the boiling point is –0.5. In –5~-20 when the product is used, butane will not be frozen. However, it would be difficult for butane to vaporize. Propane can also be used in cigarette. The boiling point for propane is –42.1, but heat of combustion is about 25% lower than that of butane.

(5)   Triggering mechanism

The triggering mechanism has to control an ignition device, to release gas from the ordinary cigarette lighter, and turn on the blower switch simultaneously.

(6)   Packaging case

The packaging case will be made from plastic material, and similar to the hair dryer in Figure 4, heat insulation material will be wrapped around the outside of the heat source.

5.         Deliverables, Schedule, Personnel, and Budget

A functional prototype and necessary design documents (design documents, drawings, test results, etc) are to be delivered in 6 months after signing the project contract. Professor Hsu, Yeh-Liang, doctoral student Yu, Chia-Chieh, and master student Ma, An-I will work part time on this project for 6 months. Table 1 shows the budget of this project. 80% of the budget should be paid to Yuan Ze University when signing the project contract. 20% of the budget should be paid to Yuan Ze University after the project is completed. We will waive the intellectual rights of any results generated from this project. However, for academic credits, if a product is patented using the design generated in this project, we do hope to be listed as inventors.