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Author: Chia-Chieh Yu, An-Yi Ma (2004-09-15); recommended: Yeh-Liang Hsu (2004-09-15).

A functional prototype of DeIcer

DeIcer is 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. It is used remotely, and does not have any power cable.

In previous work, we have confirmed that the required temperature of the outlet air can be achieved using a mixture of propane and butane as fuel. This document describes a functional prototype of DeIcer. The purpose of the functional prototype is to integrate all components to demonstrate the function of DeIcer.

1.     Layout drawings of DeIcer

Figure 1-3 show the layout drawings of DeIcer in different views. Figure 4 shows the 8 components in DeIcer: (1) protective cap, (2) flame housing, (3) burner, (4) regulator, (5) base plate, (6) blower, (7) blower holder, (8) packaging case. The blower (6) suck cold air from outside and blows it on the heating chamber (components (1)-(5)), then warm air comes out of the outlet.

Figure 1. The integration of DeIcer

Figure 2. View 1 of DeIcer

Figure 3. View 2 of DeIcer

Figure 4. Components of DeIcer

2.     Critical component

The critical technique in DeIcer design is that, how to build a combustion furnace as heat source (electrical heating has been ruled out since DeIcer should not carry any power cable), keep the combustion stable, provide enough heat, while air is constantly blown on it at 3.5 m/sec.

Figure 5 shows the heating chamber module of DeIcer, and Figure 6 shows the 5 components in the heat source. Instead of blowing air directly on the flame, the blower blows air on flame housing (5). The shape of the flame housing can be cylindrical or spherical, to provide the best efficiency. Ventilation holes on the flame housing and the protective cap (1) are carefully designed so that the combustion is complete and stable under the air flow, and flame will not come out from the outlet. The leading wire of the ignition mechanism is integrated with the burner (3) and gas regulator (4) for safe and convenient operation by the user.

Figure 5. Heating chamber module

Figure 6. Five components of the heat source

3.     The functional prototype

Figure 7 shows the functional prototype of DeIcer. There are 4 modules in the functional prototype: the heating chamber module, the blower module, the triggering mechanism module, and the sensing module. The 4 modules are described in details below:

Figure 7. Integration of functional prototype

(1)   The heating chamber module

Figure 8 shows the heating chamber (80mm×71.5mm×170.5mm) which is made by bakelite and asbestos. The heat source is contained in the heating chamber. As described in the previous section, there are 4 components in the heat source: (1) protective cap, (2) flame housing, (3) burner, (4) regulator, and (5) base plate. Figure 9 shows the burner and the regulator. The regulator can be accurately controlled to a fix gas flow rate.

Figure 8. The heating chamber

Figure 9. The burner and the regulator

Figure 10 shows the protective flame housing. The protective flame housing is made of copper, which is a good conductive material and is not easy to melt. It is designed to cover the flame to make it steadier, and to spread the heat of the flame to the housing. A leading wire of the electrical ignition is embedded in it. Figure 11 shows the gas can, which can be bought from mountain climbing stores.

Figure 10. The protective flame housing

Figure 11. The gas can

(2)   The blower module

Figure 12 shows the blower. The blower of a regular hairdryer is used. Its maximum outlet speed is 3.5m/s.

Figure 12. The blower

(3)   The triggering mechanism module

Figure 13 shows the triggering mechanism module. The electrical ignition is used to ignite the burner. A button is designed to make an electrical arc and to control the blower. Batteries provide electricity to the electrical ignition and the blower.

Figure 13. The triggering mechanism module

(4)   The sensing module

The sensing module is for measuring the performance of the prototype, and will not be included in the final product. A thermal couple measures temperature Tin of the input air. Another thermal couple measures temperature Tout at the air outlet. A thermal meter shows the difference between Tin and Tout, and this temperature change is recorded every 1 second.

Currently there are several restrictions when designing the prototype. The blower and the burner restrict the size and shape of the heating chamber and the protective flame housing. Both the burner and the gas can, which were bought from the mountain climbing store, are too big for our purpose. We need to customize these two components, but this is beyond our prototyping ability. The gas regulator needs to be customized too, so that it can be integrated with the triggering mechanism.

4.     Testing result

Figure 14 shows the operation procedures of the functional prototype. First, push and hold on the start button lightly to get the electrical arc. Then, turn on the regulator to release gas. After firing, pushes the start button to start the blower. To turn off the DeIcer, turn off the regulator first, and then push the start button again to turn off the blower. Again, if we can customize the gas regulator, we should be able to integrate it with the triggering mechanism.

Figure 14. The steps of the operation procedures

Table 1 shows the result of three different flow rates under the same testing condition. The room temperature is 27oC. As in the previous experiments, the temperature of the outlet air rises rapidly and it keeps increasing slowly. In Table 1, the mean temperature rise for 30 seconds after 60 oC is defined as DTm. As shown in Table 1, DTm decreases as air outlet speed V increases.

Table 1. The testing result of function prototype

Testing

3.6V (Three batteries)

4.8V (four batteries)

6V (Power supply)

V (m/s)

1.75

2.45

3.5

DTm (oC)

132

82

73

5.     Discussion

Several issues need to be confirmed in order to go on with the design of the 2nd generation prototype of DeIcer:

(1)       In the functional prototype, we integrated the components to demonstrate their functions, without confirming their layout. There are two possible design layout of DeIcer. Figure 15 shows the parallel layout of DeIcer. Figure 16 shows the vertical layout of DeIcer. The parallel design layout is analogous to the shape of digital camera. The vertical layout is analogous to the typical hairdryer.

Figure 15. The parallel design layout

 

Figure 16. The vertical design layout

(2)       The construction of the heating chamber is the critical design of DeIcer. The profession manufacturer called Fu-Ray will help us find the proper type of burner and gas regulator.

(3)       The gas can is also a problem of DeIcer. The gas can should be able to work over 30 minutes, and the size of the gas can should be as small as possible. The fuel of mix of Propane and Butane should be used in –15oC.

(4)       The outlet temperature changes should be controlled in 85oC.

(5)       The triggering mechanism should be the one button to start the DeIcer.

(6)       The professional manufacturer called Raeider will provide a new type of fan, which can work in AA batteries and blow strong flow for 30minutes.

(7)       The isolation materials should be added to prevent users from burning their hands and DeIcer.

(8)       Safety issues need to be discussed.