General background of Paltrier device: Paltrier devices are solid-state devices used for cooling and heating. They occupy a niche market due to their small size, cost effective manufacture and accurate temperature control. Paltrier works bet utilizing the difference in the conduction band energies of two materials.
When electron migrate across a junction of two unlike materials they may either absorb or liberate heat energy. Experimental Methods and set-up Required Equipments: Paltrier device, dual power supply, heat sinks, AY blocks, enclosure, screw threads and nuts, millimeters and thermocouples, access to a cooler refrigerator and compressor based refrigerator. We separate the experiment into three major parts, First, to define which combinations of equipments gives the coldest temperature at the cold side. This steps involved combining equipments in different orders.
Secondly, Construct a self-designed cooling box and measure the coldest temperature we could achieved. Finally, measure the cooling curve of the cooler refrigerator and compressor based refrigerator and determine their efficiency. Compare the efficiency of self-designed cooling box, cooler refrigerator and compressor based refrigerator.
Finding out the best configuration of equipments that cools the Paltrier device most efficiently (varying the voltage input and change of polarity was also done). Connect Paltrier device with power supply and monitor each surface of device using thermocouples.
Note that we exceeded the maximum allowed current of voltage input in order to determine which voltage input cools the Paltrier device down most efficiently. Started organism heat sink, fans, thermal compounds and Paltrier device is differed configurations and observe the outcome of these configuration. Adopt the best configuration to design the best cooling box in the second part if the experiment. Placed a fan beside the heat sink and repeat the measurement. The power input remain as 10. 0+0. 5 V. Then the cold side temperature is measured. Then input an AY slab between Paltrier device and the heat sink.
Measured the cold side temperature. Applied thermal compound at the bottom of the Paltrier vice(hot side), measured the cold side temperature. (Slab is removed) Now, added another fan (two fans in total) beside the heat sink. Measure the cold side temperature. Finally , we placed an AY slab between two Paltrier deviance applied thermal compound on the hot side. Measured the cold side temperature. Now remove all the configuration with only power supply, Paltrier device and thermocouple remain. We would like to observe the effect of change polarity of the Paltrier device.
Measure the temperature of both sides of the device for 200 s. Then swapped the polarity of the input and observed the effect. By doing the above analysis we are able to design a cooling box. The above demonstration allows us to figure the different configuration bits by bits. Now we start construct a cooling box.
Initial Design of cooling box Seated the input voltage and current as 7. +- 0. 5 V and current as 1. 8 +- 0. 1 A. Thermal compound was applied between the Paltrier device and large AY slab. Took measurements of temperature inside the fridge in every 1 minute interval. Uncertainty is taken as half of the last significant figures given by the temperature. Followed the suggested improvement discussed in section 2 of the discussion section, we sat the fridge upside down. We also increased the setting of input by Mathematics for Students Input voltage was 12. 0 +- 0. 5 V and input Printed voltage and current. Current was 3. 8 +- 0. 1 A for 15 minutes.
Again, the temperature inside the cooling box is measured in every 1 minute interval. 3 slab. Took measurements of temperature inside the fridge in every 1 minute f input voltage and current. Input voltage was 12. 0 +- 0. 5 V and input current was 3. 8 +- 0. 1 A for 15 minutes. Again, the temperature inside the cooling box is measured in every 1 minute interval.
Examination of the Cooler fridge and the Compressor based fridge This section mainly to repeat the measurement undertook in section for cooler fridge and compressor based fridge. For cooler fridge, set the input voltage as 9. +- 0. 5 V and current as 3. 0 +- 0. 5 A. Measure the temperature inside the cooler fridge in every 1 minute over minutes length. For the compressor based fridge, et the input voltage as 240+- 1 V and current as 0. 4 +- 0. 1 A. Measure the temperature inside the cooler fridge in every 1 minute over minutes length. Finally, measured the volume of the self-designed cooler box, cooler fridge and compressor based fridge. Calculated the efficiency of these devices and compare the results.
Results and Discussions: Surface temperature of Paltrier device: Cold Side: 28. +- 0. 2 C Hot Side: 45. 8 +- 0. 2 C Errors comes from fluctuating from readings recorded by thermocouple. The temperature difference between the hot and cold side of Paltrier device is smaller than expected. The cold side has temperature at room temperature . Suggested reason is that the Paltrier device is too thin that heat liberated at hot side travels to the cool side by conduction which heat up the cool side of the Paltrier device. Surface temperature of the cold side of the Paltrier device on the heat sink: 16. 2 +- 0. 1 C It is lower than the room temperature.
The uncertainty was smaller than because less temperature fluctuation in the thermocouple readings. Table 1 : Voltage of power supply and the corresponding cold side temperature Voltage V 0. 5 Cold surface temperature of Paltrier C 3. 0 16. 2 5. 0 8. 8 7. 5 4. 1 10. 0 1. 3 0. 1 From table 1, notice that the Paltrier device cools most efficiently at 10 V as the input voltage. When we used 10 V from the power supply, the cool side of the Paltrier device was reduced to below O C. Ice formed on the surface. Ice was removed before the next measurements.
Surface temperature of the cold side of the Paltrier device on the heat sink and cooling fan: 3. 5 +- 0. 5 C The fluctuations is large due to the fan drawing air through cold side of Paltrier device. When we elevated the Paltrier device using as AY slab under the heat sink so that the device is above the level of the fan, we achieved temperature of cold side as -1. +- 0. 2 C. This is attributed to the heat sink. Heat moves quicker through conduction as the fan draws cool air through the fans of the heat sink. This allows heat to be conducted quicker away from hot side of Paltrier device and hence cool more efficiently.
Surface temperature of the cold side of the Paltrier device with AY slab between the device and heat sink and a fan beside it: 4. 0 +- 0. 5 C We suggested the reading is wrong since ice is formed on the surface of the cold side of the device. When we used hand to feel the temperature, it is actually colder than the experiment we did without AY slab. Suggested reason is that the late slowed the conduction of heat to the fins of the heat sink. This caused heat to be conducted away from the hot side of the Paltrier device more slowly and hence a lower temperature was not observed.
Printed Mathematics for applied Surface temperature of the cold side of Believability with Students thermal compound on the hot side: -3. 6 +- 0. 3 C We also observed that in this configuration, the Paltrier device also cools significantly faster with ice framing on from hot side of Paltrier device and hence cool more efficiently. 4 Surface temperature of the cold side of the Paltrier device with AY slab between he device and heat sink and a fan beside it: 4. 0 +- 0. 5 C hence a lower temperature was not observed.
Surface temperature of the cold side of Paltrier device with applied thermal significantly faster with ice framing on its surface within 30 seconds. This is attributed to the heat transfer compound improving thermal contact between Paltrier device and the heat sink. This allowed the heat from hot side of the device to be conducted to the heat sink more quickly. Compound on the hot side with two cooling fans: -3. 8 +- 0. 3 C The improved performance can be attribute to the improve flow around fins of the heat side. Thus, removed heat from the system more quickly. Cold side temperature of two Paltrier device: -6. +- 0. 2 C This is the best result we obtained so far since the temperature is cooled by two Paltrier device.
