Week 11 : Result of the core temperature

Week No : 11                                                                                                          Date : 5/4/2012

Title of Activity : Result of the core temperature (38^oC ).

Objective :
1) To figure out the suitable result for the end of actual core temperature.
2) To determine the design of temperature graph.
3) To complete up for the final progress of project.

Content / Procedure :
1) All the hardware & software parts are combine altogether.
2) The LM35 is used as heat sensor to detect the changing of temperature.
3) Testing part will be occurred by using 2 bulbs and 3 bulbs. The tables for both results will be constructed.
4) By setting up the  ambient temperature (Ta) with starting of 26⁰C. Then, the setting point (S.P) button will be pushed to increase the temperature. Thus, the differences of emitting light happened on the bulbs. 
5) Then, the results from the difference type of bulbs ( 2 bulbs / 3 bulbs ) will be graphed on the graph of temperature.
6) Analyse from the both results.

Result and Analysis :
1) Result & graph result of temperature in smart phototherapy by using 2 bulbs.

                     Figure 1 : Result & graph result of temperature in smart phototherapy by using 2 bulbs


- The ambient temperature (Ta) is set with (26⁰C). It took 7 seconds to increase to (27⁰C). From 0 second to 44seconds, the PWM circuit gives a 100% in performance of duty cycle.
- The set point of temperature (S.P) is (37⁰C). 
- At (30⁰C), the PWM circuit stabilizes the heat produced by bulbs by changing the performance of duty cycle at 90% and 50%.
 



2)  Result & graph result of temperature in smart phototherapy by using 3 bulbs.

                 Figure 2 : Result & graph result of temperature in smart phototherapy by using 3 bulbs


- The ambient temperature (Ta) during experimenting was (26⁰C). It took 8 seconds to increase to (27⁰C). From 0 second to 40seconds, the PWM circuit gives a 100% in performance of duty cycle.
- The set point of temperature (S.P) is (37⁰C).
- At (30⁰C), the PWM circuit stabilizes the heat produced by bulbs by changing the performance of duty cycle at 90% and 50%.

3) Results on the Pulse Width Modulation (PWM)





Figure 3 : Results on the Pulse Width Modulation (PWM) 

- 100% performance of duty cycle : Refer to the Figure 3, at this stage, the temperature increase until 30⁰C which is 7⁰C before the set temperature in 40seconds.
- 90% performance of duty cycle : Refer to Figure 3, the temperature will increase until it reaches at the set point temperature, 37⁰C. This increment is happened in 112 seconds. At this stage, the PWM circuit will turn to 50% of duty cycle’s performance.

- 50% performance of duty cycle : At this stage, the PWM circuit controls the heat produce either in 50% or 0% (cut-off) to maintain the temperature at 38⁰C in the compartments.


Conclusion :
1) The LM35 is chose to be a heat sensor because of it generates a higher output voltage and proportional to the Celsius (^oC) temperature.
2) Regarding on the graph in Figure 1, it shows that there is no overshoot temperature when using 2 bulbs.
3) Regarding on the graph in Figure 2 , it shows that there is an overshoot temperature when using 3 bulbs. The overshoot was in (2⁰C) over the set temperature. When the temperature was (2⁰C) more than set temperature, the PWM circuit will cut off and no heat was produced by bulb. The temperature decreased to set temperature.
4) The PWM method is used because of it is able to control the heat produced by the heat elements in percentage, 100%, 90% or 50%.