ARM Based Climate Controlled Wearable Jacket

INTERNATIONAL JOURNAL FOR TRENDS IN ENGINEERING & TECHNOLOGY VOLUME 4 ISSUE 2 – APRIL 2015 - ISSN: 2349 - 9303

ARM Based Climate Controlled Wearable Jacket R.Naghalakshimi II year Student, M.E. Embedded Systems Technologies Sri Ramakrishna Engineering College Coimbatore, India nagramval@gmail.com

Dr. S. Jayanthy Professor, Department of ECE Sri Ramakrishna Engineering College Coimbatore, India sjayanthyabi@gmail.com

Abstract— Thermo-electric (TE) technology is used in both electricity generation and air-conditioning. The Thermo-electric coolers(TEC) uses Peltier effect which converts the electrical energy applied from the ends of the Thermo-electric module into the temperature difference. The main objective of the work is to design a highly reliable and wearable jacket that controls extreme temperatures say working in thermal power plants, within the jacket. The extreme temperatures can be monitored using temperature sensors placed on both sides of the Thermo-electric cooler module and controlled using ARM LPC2148 Microcontroller. In Industries, this jacket provides a more practical and safer solutions for human working under extreme temperatures. Furthermore, this jacket can also be applied as a good warmer one for human beings working in cold regions(say Polar regions).

Index Terms— ARM7 LPC2148 Microcontroller, Heat dissipation, Monitoring and Controlling Temperatures, Peltier effect, Temperature Sensor, Thermo-electric Cooler (TEC) Module, Wearable Jacket.

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INTRODUCTION

Thermo-electric cooling is a way to remove thermal energy from a medium, device or component by applying a voltage of constant polarity to a junction between dissimilar electrical conductors or semiconductors. A thermo-electric cooling system typically employs a matrix of semiconductor pellets sandwiched in between two large electrodes. When a DC voltage source is connected between the electrodes, the negatively-charged side becomes cooler while the positively-charged side becomes warmer [3]. The negative electrode is placed in contact with the component, device or medium to be cooled, while the positive electrode is connected to a heat sink that radiates or dissipates thermal energy into the external environment.

A Peltier cooler can also be used as a thermo-electric generator.

When operated as a cooler, a voltage is applied across the device, and as a result, a difference in temperature will build up between the two sides ( the Peltier effect). When operated as a generator, one side of the device is heated to a temperature greater than the other side, and as a result, a difference in voltage will build up between the two sides (the Seebeck effect).

A single-stage Thermo-electric cooler will typically produce a maximum temperature difference of 70 °C between its hot and cold sides. The more heat moved using a TEC Module, the less efficient it becomes, because the TEC Module needs to dissipate both the heat being moved, as well as the heat it generates itself from its own power consumption. The amount of heat that can be absorbed is proportional to the current and time [1].

In general, thermo-electric cooling is less efficient than compressor-based refrigeration. However, in situations where thermal energy must be transferred away from a solid or liquid on a small scale, a thermo-electric cooling may be more practical and cost-effective than a conventional refrigeration system [2]. Other advantages of the thermo-electric cooling include minimized cost, power consumption, portability, long operating life and minimal maintenance requirements.

Thermo-electric cooling is used in electronic systems and computers to cool sensitive components such as power amplifiers and microprocessors. The technology can also be useful in a satellite or space probe to moderate the extreme temperatures that occur in components on the sunlit side and to warm the components on the dark side [4].

So, Thermo-electric cooler modules can be implemented in the design of climate controlled wearable jacket which helps people working in extreme temperatures. The extreme temperatures can be monitored using temperature sensors placed at the top and bottom the thermo-electric cooler module and controlled using ARM7 LPC2148 Microcontroller embedded with the module.

In order to control the heat dissipated at the hot side of the Thermoelectric cooler module, a small liquid pump and heat sink can be connected using Relay. To control the extreme temperatures and provide a temperature that is tolerable to people, a relay is connected to control the power supply of the Thermo-electric cooler module.

Hence, the Thermo-electric cooler module makes an effective climate controlled wearable jacket which provides a more safer and practical solutions to people working in extreme temperatures. This module makes the design very cheap and reliable. The Climate Controlled Wearable jacket is implemented in a single system using a Thermoelectric cooler module along with a heat sink prototype. In this paper, Section II describes about the proposed Climate Controlled wearable jacket, system design, Programming in IDE, Thermo-electric cooler Module and Software algorithm. Section III displays the proposed system design. Section IV explains the various experimental results took at various instances. Finally, Section V deals with the conclusion and future work.

2 PROPOSED CLIMATE CONTROLLED WEARABLE JACKET 2.1 Existing System Currently, the Thermo-electric cooler modules are used in designing

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INTERNATIONAL JOURNAL FOR TRENDS IN ENGINEERING & TECHNOLOGY VOLUME 4 ISSUE 2 – APRIL 2015 - ISSN: 2349 - 9303 cooling products for custom/OEM applications, telecommunications, consumer electronics and cold plates for laboratories [5]. They are used in scientific applications, digital cameras and charge coupled devices(CCD) to minimize thermal noise and optimize sensitivity.

Also, the heat dissipated in thermo-electric module made it less efficient. Further, it caused more power consumption. So, the Thermo-electric module is incorporated with the heat sink and liquid pump for proper heat dissipation thus controlling extreme temperatures to tolerable temperatures for people who wear it. The main advantage of the climate controlled wearable jacket is that the system design is less complex, easily controllable, long life, reliable, consumes less power, small in size and weight and it provides more affordable and needful solutions to people.

2.2 System Design The system consists of two temperature sensors placed at the top and bottom of the Thermo-electric cooler module. Two different temperature values are monitored by the two temperature sensors which are connected to the ADC port of the ARM7 LPC2148 Microcontroller. For visual inspections, these values are displayed in the LCD. In order to control the heat dissipated at the hot side of the Thermo-electric cooler module, a small liquid pump and heat sink is connected to the Microcontroller using Relay. The block diagram of the system is shown in the Fig 1. To control the extreme temperatures and provide a temperature that is tolerable to people, another relay is connected to control the supply of power to the Thermo-electric cooler module.

the USB port of a PC to the target hardware. This enables us to download, test and debug the final executable hex code generated from the Keil IDE to the target hardware.

Since ARM7 LPC2148 Microcontroller Board is used in this system, which is more employed in industrial automation and consumer electronics, it has capability to consume less power and work with more efficiency. It is very easy to program in the Keil µVision IDE because IDE has inbuilt libraries for individual components, Middleware toolchain, etc. Since this system fully deals with monitoring and controlling the Thermo-electric cooler module and provide necessary controlled power supply to it, the Microcontroller unit is programmed using the Keil IDE. The temperature values are monitored via ADC port of the Microcontroller through which the temperature sensors are connected. For visual inspections, these values are displayed in the LCD. The Thermo-electric cooler module is controlled by using Relay which is connected to the Microcontroller. To achieve the system monitoring and controlling architecture, we should include the library files for initializing the LCD and clock frequency. The initialization, programming, debugging, simulation and downloading to the target Microcontroller, all can be done using the Keil µVision IDE and corresponding Keil ULINK-JTAG adapter. The Keil µVision IDE programming environment is mentioned in Fig 2.

Fig. 2. Programming in Keil µVision IDE

2.4 Thermo-electric cooler Module Fig. 1. Block Diagram of Climate Controlled Wearable Jacket

2.3 Programming in the KEIL IDE The Keil µVision IDE is a simple integrated development environment (IDE) that runs on regular personal computers and provides toolsets for a powerful, easy to use and easy to learn environment for developing embedded applications. It include the components we need to create, debug and assemble our C/C++ source files, and incorporate simulation for microcontrollers and related peripherals. It also have RTX RTOS Kernel Library, Device Database, Debugger and Analysis tools and complete device simulation. It also has RTOS and Middleware components for implementing time-critical softwares and shorten the development cycle. Further, it has Flash File system, USB Device Interface and CAN Interface. The Keil ULINK-JTAG family of adapters connect

Thermo-electric cooling uses the Peltier effect to create a heat flux between the junction of two different types of materials. A Peltier cooler, heater, or thermo-electric heat pump is a solid-state active heat pump which transfers heat from one side of the device to the other, with consumption of electrical energy, depending on the direction of the current. Such an instrument is also called a Peltier device, Peltier heat pump, solid state refrigerator, or thermo-electric cooler (TEC) as shown in the Fig 3. It can be used either for heating or for cooling, although in practice the main application is cooling. It can also be used as a temperature controller that either heats or cools.

A Thermo-electric cooler module consist of two unique semiconductors, one n-type and one p-type, because they need to have different electron densities. The semiconductors are placed

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INTERNATIONAL JOURNAL FOR TRENDS IN ENGINEERING & TECHNOLOGY VOLUME 4 ISSUE 2 – APRIL 2015 - ISSN: 2349 - 9303 thermally in parallel to each other and electrically in series and then joined with a thermally conducting plate on each side.

Temperature goes below 20°C, relay that controls pump gets tripped OFF. But Thermo-electric cooler Module still cools since the relay that controls it, is ON. Step 9: When the Temperature goes below 16°C, relay that controls Thermo-electric cooler module also gets tripped OFF. Now, Thermoelecric cooler module gets heated up to Normal temperature say 25°C. When the temperature goes above 23°C, both the relay gets turned ON and loop back to step 6.

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Fig. 3. Thermo-electric Cooler (TEC) Module When a voltage is applied to the free ends of the two semiconductors there is a flow of DC current across the junction of the semiconductors causing a temperature difference. The side with the cooling plate absorbs heat, which is then moved to the other side end of the device where the heat sink is. Thermo-electric coolers are typically connected side by side and sandwiched between two ceramic plates. The cooling ability of the total unit is then proportional to the number of Thermo-electric coolers in it.

PROPOSED SYSTEM DESIGN

The Climate Controlled Wearable Jacket consist of Thermo-electric Cooler module interfaced with the ARM7 LPC2148 Microcontroller as shown in Fig 4. This system consists of two temperature sensors placed at the top and bottom of the Thermo-electric cooler module.

Two different temperature values are monitored by the two temperature sensors which are connected to the ADC port of the ARM7 LPC2148 Microcontroller. For visual inspections, these values are displayed in the LCD. In order to control the heat dissipated at the hot side of the Thermo-electric cooler module, a small liquid pump and heat sink are placed on it and connected to the Microcontroller using Relay. To control the extreme temperatures and provide a temperature that is tolerable to people, another relay is connected to control the supply of power to the Thermo-electric cooler module.

2.5 Software Algorithm The system is programmed in such a way that the temperature sensors monitor the temperature values, input the values to the Microcontroller via ADC port and the values are displayed in the LCD for visual inspections. In order to control the heat dissipated at the hot side of the Thermo-electric cooler module, a small liquid pump and heat sink are placed on it and connected to the Microcontroller using Relay. To control the extreme temperatures and provide a temperature that is tolerable to people, another relay is connected to control the supply of power to the Thermo-electric cooler module. The algorithm for such system is as follows.

ALGORITHM Step 1: Include header files for Interfacing the LCD with the Microcontroller unit.

Step 2: Initialize VPBDIV register as 0x02 for setting clock frequency of 30 MHz. Step 3: Initialize Analog ports for interfacing two temperatures to measure two different temperature readings of Thermo-electric Module.

Step 4: Initialize ports for the LCD operating in 4-bit Mode.

Step 5: Initialize ports for a relay that controls liquid pump and the heat sink, and another relay that controls Thermo-electric module.

Step 6: Begin the infinite while loop, read the Temperature values from sensors in ADC port and display the values in the LCD. Step 7: Initially, Thermo-electric Cooler Module will start cooling from Normal temperature. So, both the relays will be ON. Step 8: Thermo-electric cooler Module starts cooling and when the

Fig. 4. Climate Controlled Wearable Jacket

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EXPERIMENTAL RESULTS

Initially, Thermo-electric Cooler Module will start cooling from Normal temperature. So, both the relays will be ON. The two different temperature readings are displayed in the LCD as shown in Fig 5.Thermo-electric cooler Module starts cooling and when Temperature goes below 20°C, Pump control relay gets tripped OFF. But Thermo-electric cooler Module still cools since the relay that controls it, is in ON condition. When Temperature goes below 16°C which is intolerable for human, Thermo-electric cooler module control relay also gets tripped OFF.

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CONCLUSION

Thus the climate controlled wearable jacket monitors the extreme temperatures, controls and provides tolerable temperature to the people who wear it using Thermo-electric cooler Module. The heat dissipated in this system is controlled at a maximum rate using a heat sink and a liquid pump. Thus the system eliminates the conventional methods of handling heat dissipation. The Ultra thin Thermo-electric Cooler Module provides more afforable and needful solutions to the people making the system less complex, very less power consumption, small in size and weight.

Fig. 5. Different Temperature values displayed in LCD Now, Thermoelecric cooler module gets heated up to Normal temperature say 25°C. When temperature goes above 23°C, both the relay gets turned ON. The observations are being made for the climate controlled wearable jacket for different conditions and the values are being tabulated as shown in the Table 1. From the table, it is inferred that when Temperature goes below 20°C, Pump control relay gets tripped OFF. But Thermo-electric cooler Module still cools since the relay that controls it, is in ON condition.

TABLE 1 OBSERVATIONS MADE AT VARIOUS INSTANCES Temperature at Cold Side (°C)

Temperature at Hot Side (°C)

25.4 23.8 21.3 19.8 17.6 16.4 15.9 16.7 18.6 21.2 22.8 23.1 22.9 21.6 19.4

27.7 27.9 28.2 28.5 29.1 29.2 29.7 29.2 28.8 28.1 28.0 27.4 28.0 28.5 28.3

Pump Control Relay Status (ON/ OFF) ON ON ON OFF OFF OFF OFF OFF OFF OFF OFF ON ON ON OFF

Thermo-electric Cooler Module Control Relay Status (ON/OFF) ON ON ON ON ON ON OFF OFF OFF OFF OFF ON ON ON ON

When Temperature goes below 16°C which is intolerable for human, Thermo-electric cooler module control relay also gets tripped OFF. Then, Thermoelecric cooler module gets heated up to Normal temperature say 25°C. When temperature goes above 23°C, both the relay gets turned ON.

As Thermo-electric Cooler Module works in Peltier Cooling Effect, the system can be implemented in wearable jacket that can provide tolerable and controlled temperature to the people wearing it.

In the Future, if the system is implemented in thin fabric designed jacket, this system would be a milestone in the field of Wearable Electronics for sure. The work can also be extended by using increased figure of merit Peltier Modules and efficient heat exchange technology.

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