Sci. Technol. Arts Res. J., Oct-Dec 2015, 4(4):

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1 DOI: ISSN: (Print) and (Online) Science, Technlgy and Arts Research Jurnal Sci. Technl. Arts Res. J., Oct-Dec 2015, 4(4): Jurnal Hmepage: Design and Implementatin f Micrcntrller based Autmated Air Cnditining Cntrl System fr Refrigeratr Truck Frezer Getachew 1, Helen Nekatibeb 1, Samuel Wrkineh 1, TesfayeYitbarek 1, YibeltalGelaye 1 and Taye Girma 2* 1 Department f Cmputer Engineering, Micrlink Infrmatin Technlgy Cllege, Addis Ababa, Ethipia 2 Department f Cmputer Science, St.Mary s University, P.O. Bx: , Addis Ababa, Ethipia Abstract In rder t transprt temperature sensitive agricultural r factry prducts fr the markets which demand high quality prducts, using special freight transprtatin like refrigeratr truck facilities is mandatry. Hwever, the currently available refrigeratr trucks have n dynamically cntrlled system as expected t be. Therefre, the aim f this paper is t design, simulate and implement micrcntrller based air cnditining cntrller t mnitr and cntrl the Refrigeratr temperature by using a temperature sensr, LM35 and this sensr mnitrs the temperature f the refrigeratr based n the predefined temperature value under the cntrl f PIC016F877A micrcntrller. The system displays the temperature and the status f the heater, cmpressr and fan as ON r OFF n the LCD. The input temperature in the range f 55 t +150 C is cmpared with the value stred by the user and if the temperature ges belw the predefined pint f temperature value, the heater and fan switch will be ON and cmpressr will be OFF; if temperature ges between predefined temperature value nly fan switched ON, and when the predefined temperature value ges abve, the fan and cmpressr nly switched ON. A 24V f each three relays are interfaced with the micrcntrller in rder t make the respective fan, heater and cmpressr switched ON/OFF. The simulatin result is checked fr cnsistence and crrectness with the result f physically implemented refrigeratr truck cntrller. Cpyright@2015 STAR Jurnal, Wllega University. All Rights Reserved. Original Research Article Infrmatin Article Histry: Received : Revised : Accepted : Keywrds: Micrcntrller Air cnditining Refrigeratr Truck Sensr *Crrespnding Authr: Taye Girma tayegirma@gmail.cm INTRODUCTION Air cnditining is the prcess f changing r ON-OFF type clsed lp cntrlling system which in turn mdifying the prperties f air in the specified area, in this has an impact in the develpment endeavr. case the refrigeratr truck; the ultimate gal in air cnditining is t distribute the temperature t mre MATERIALS AND METHODS cmfrtable cnditins, typically with a target f Materials distributing the cnditined air t imprve thermal cmfrt The fllwing hardware and sftware resurces are and indr air quality. Therefre, temperature cntrlling used in rder t design and implement micrcntrllercntrlling system. is a prcess in which change f temperaturee f a space r based autmated refrigeratr truck AC an bject r bth is detected s that the flw f heat energy int r ut f the space is cntrlled and adjusted Hardware Requirements t achieve a better and desired temperature (Wikipedia, 2015). Micrcntrller (PIC16F877A): It is the central part f the system that cntrls the entire system by prcessing The existing traditinal and mstly affrdable type f the input and utput signals. It cntinuusly receive input AC cntrlling system has lts f prblem since it is temperature signal frm the sensr and then prcess the manually manipulated. As a result f this it is prne fr infrmatin and decides based n the predefined set pint errr. In additin t this, the measurement is nt as such f temperature cnditin. accurate and als the expected utput is displayed using analg display system. Beside this almst all the currently Temperature Sensr: The LM35 series are precisin existed refrigeratr trucks are mstly cmplemented with integrated circuit temperature sensrs, whse utput cling system. Therefre, this paper aimed t design, vltage is linearly prprtinal t the Celsius temperature simulate and implement micrcntrller based air with a gradient f 10mV/ C (Thein Thein Se et al., 2014; cnditining cntrller fr refrigeratr truck by integrating Sxma). This sensr is used t sense the refrigeratr bth the heating and cling element and cme up with inside van temperature cnditin between -55 C and 150 C and then transmit t the micrcntrller fr further A Peer-reviewed Official Internatinal Jurnal f Wllega University, Ethipia 131

2 Frezer Getachew et al., prcessing (Tassu et al., 2006). The circuit cnnectin fr LM35 temperature sensr is als given in (Figure 1) (Thein Thein Se et al., 2014). Sci. Technl. Arts Res. J., Oct-Dec 2015, 4(4): cnditin f the micrcntrller utpu based n ASCII standard set f characters and mathematical symbls. It is indicated in (Figure 2). C B A D E F G H I J K VSS VDD VEE 4 5 RS E 6 RW 7 8 D0 9 D1 10 D2 11 D3 12 D4 13 D5 D7 14 D6 Figure 1: Circuit cnnectin f LM35 sensr Liquid Crystal Display (LCD): Micrcntrller interfaced LCDs are mstly used in many applicatins. These days, LCD replaced mst f the LEDs in system design because f lw pwer cnsumptin and flexible graphics display. This intelligent LCD mdule can shw 160 different characters (Thein Se et al., 2014). It displays every Figure 2: A 16 character x 2 lines LCD pin cnfiguratin DC Pwer Supply: stable DC vltage is needed fr cnsistent peratin fr the entire circuit. The micrcntrller needs +5DC vlt, the three relays each (24DC vlt), and ther cmpnent in the system als need stable DC vltage. As can be shwn belw a variable regulatr can be set t prduce +5v and +24v by varying the utput in rder t btain the desired DC utput (Figure 3). Figure 3: Pwer supply circuit fr truck refrigeratr cntrller Relay: is an electrical switch that pens and clses under the cntrl f the micrcntrller. Permanently the relays gets psitive DC vlt frm the pwer supply and ppsite DC frm the micrcntrller in rder t amplify the respective subsequent refrigeratr truck electrmechanical system. Push Buttn: is used t RESET the system. Other Cmpnents: semicnductr and basic electrnics cmpnents such as dide, transistr, resistrs and capacitrs are als used during system design (Ams and James, 1959). Sftware Requirement There are different ways t prgram PIC16F877A micrcntrller either using a highly levell prgramming language like C r using an assembly language. In this prject we used the prcedural riented language f (C) t prgram the micrcntrller. The C prgramming language has a lt f advantage cmpared t ther prgramming languages: It has many libraries that prvide built-in functins and pssibilities fr user t define arbitrary functins. The cmpiler ptimize the cde fr faster executin, easy t learn syntax and easily prtable. Prteus 8 prfessinal and MPLAB IDE I v8.92 are als used. Methdlgy T design, simulate and implementt the micrcntrller based autmatic air cnditining cntrl system fr refrigeratr truck the fllwing prcedures are fllwed, Identifying the Requirement Identifying the Required Hardware Micrcntrller (PIC16F877A), Resistr (10kΩ), Dide (nrmal p-n and LED), DC pwer supply (5V, 12V, and 24V), Switch, Transistr, Relay (24V), LCD (LM016L), Temperature Sensr (LM35), and capacitrs (1nf x4, 2.2nf) are used Identifying the required Sftware C-Prgramming language t prgram the micrcntrller Prteus 8 prfessinal fr circuit designing and simulatin MPLAB IDE v8.92 fr cde develpment envirnment 132

3 Frezer Getachew et al., Designing and System Mdeling In this step the system flw diagram is develped t design and integrate each cmpnent t frm the required system and C cde is written t run the entire system. Simulating the System Integrating the circuit design with the C-prgram cde. Based n each cmpnent specificatin interfacing with the micrcntrller and then lading the prgram n prteus and n micrcntrller. Sci. Technl. Arts Res. J., Oct-Dec 2015, 4(4): binary bits. The cnverted binary data frm the ADC is applied t micrcntrller and then the micrcntrller reads binary data frm ADC. Finally, the micrcntrller cnverts it t suitable frm and perfrms different peratins based n the value f temperature read frm ADC. The LCD is used t display the data given by micrcntrller. Micrcntrller can turn n the relay(s) based n the cnditin defined during initializatin (set value). The system functinal diagram fr refrigeratr truck cntrller is given in (Figure 4). Testing the System After lading the cde n the Prteus and integratin f the circuit design with the cde the system was tested fr its crrectness and perfrmance. LCD Physical Implementatin and Experimentatin After simulatin and simulatin testing, all cmpnents are tested fr prper functinality and then sldered tgether t get system circuit. Testing the Physical Implementatin In this step, injecting the cde t the micrcntrller was perfrmed and then testing was cnducted t cnfirm the simulatin result by physically implemented system. Temperature Sensr Micrcntrller Relay 1 Relay 2 Fan Heater System Design and Simulatin The system design basically cnsists f micrcntrller as a central prcessr f the entire cntrl peratin. The temperature sensr gives the analg utputt vltage based n the temperature f the refrigeratr truck rm. This analg vltage is feed t the ADC (built-in inside the micrcntrller). The ADC then cnverts the analg input vltage frm the temperature sensr int equivalent Relay 3 Cmpressr Figure 4: Functinal blck diagram fr refrigeratr truck cntrller Figure 5: Circuit Diagram fr truck refrigeratr cntrller result after RESET The PIC16F877A micrcntrller receives infrmatin signal thrugh LM35 sensr frm external envirnment (level f temperature). The sensr checks the envirnment in every five secnds. The micrcntrller prcesses the digital signal and then transmits cmmand t the respective relays based n the cnditins 133

4 Frezer Getachew et al., Sci. Technl. Arts Res. J., Oct-Dec 2015, 4(4): predefined set value. If the checked set pint f temperature is belw 2 C, the micrcntrller cmmands relay ne and relay three turned ON- t make the fan and heater switched ON respectively; and relay tw switched OFF- t make the cmpressr turned OFF. If the checked temperature is between 2 C and 6 C, the micrcntrller directs relay tw and three switched OFF (cmpressr and heater) and relay ne switched ON. If the temperature cnditin is greater r equal t 6 C, the micrcntrller cmmands relay ne (fan) and relay tw (cmpressr) switched ON and relay three (heater) switched OFF. Relay ne (fan) always switched ON t make the air diffused r balanced thrughut the van f cld truck. Whether each respective relays functins r nt, that is enables the fan, cmpressr, and heaters switched ON is bserved thrugh the LEDs which are cnnected t the fun, cmpressr, and heater. Als if each respective LED s are switched ON, the respective relays are functin prperly, and the push buttn is used t RESET and the system starts again. System Flw Diagram The fllwing flw chart illustrates the flw f peratins f the verall autmatic AC cntrller system fr refrigeratr truck. A C-prgramming cde is emplyed t run the entire system. Fan Cntrller ON D untill RESET Read Temp frm temp sensr N <=1.9 C Is Temperature Yes >=5.9 C Heater ON state Cmpressr & Heater OFF state Cmpressr ON state Display the status n LCD End Figure 6: System flw diagram fr refrigeratr truck cntrller RESULT AND DISCUSSION The sensr, LM35, checks the envirnment in every five secnds t cllect infrmatin frm the external envirnment s that micrcntrller uses this infrmatin fr generating cmmands t send t relays depending n the predefined cnditins. Whether each respective relays cnnected t fan, cmpressr, and heaters are prperly functining r nt are cntrlled thrugh the LEDs which are cnnected t the fan, cmpressr, and heater. That means, if each respective LED s are switched ON, the respective relays are wrking prperly. The simulatin f the system is perfrmed based n the fllwing cnditins, Cnditin 1: If the sensr finds temperature belw 1.9 c, the micrcntrller cmmands relay ne and relay three t be turned ON s that the fan and heater switch ON; and relay tw switch OFF s as t make the cmpressr will turn OFF. Belw in (Figure 7), the sensr reads truck temperature f (T c = 0.8) as displayed in LCD. As the result, the micrcntrller cmmands the respective relays t turn ON s as t ON the fan and heater as indicated n the LCD and the respective LEDs (the red and yellw) has als switched ON. 134

5 Frezer Getachew et al., Sci. Technl. Arts Res. J., Oct-Dec 2015, 4(4): Figure 7: Refrigeratr Truck Cntrller result when temperature is belw 1.9 C Cnditin 2: If the sensr senses a temperature between 2 and 5.9 C,, the micrcntrller directs relay tw and three t be switched OFF (cmpressr and heater) and relay ne switched ON. The sensr finds a temperature f 2.30 C as displayed n the LCD and micrcntrller cmmands the fan fa t be turned ON (red LED) and the he ther tw LEDs are t be switched OFF state (cmpressr and heater). This is shwn belw in (Figure 8). c result when temperature is between 2 C and 5.9 C Figure 8: Refrigeratr truck cntrller Cnditin 3: If the sensr reads a temperature greater r equal t 6 C, the micrcntrller cmmands relay ne (fan) and relay tw (cmpressr) t be switched ON and relay three (heater) t be switched OFF. Relay ne (fan) (f always switched ON t make the air diffused r balanced thrughut the van f cld truck. If the sensr reads a truck temperature f 6.5 C as displayed n the LCD, the micrcntrller cmmands the fan and cmpressr t be turned ON (red and yellw LED) and this is depicted in figure

6 Frezer Getachew et al., Sci. Technl. Arts Res. J., Oct-Dec 2015, 4(4): Figure 9: Refrigeratr truck cntrller c result when temperature is abve 6 C Cnditin 4: Reset Cnditin, when hen the refrigeratr truck reaches its target destinatin, the entire system will be rested thrugh re-setted buttn s that the system starts again. That means, the micrcntrller cmmand the LCD t display the readiness f the system with the default temperature (T C = 0.00) and the status f fan and heater t be n the ON state as it is indicated in figure f 10. Figure 10: Refrigeratr truck cntrller result after RESET 136

7 Frezer Getachew et al., Sci. Technl. Arts Res. J., Oct-Dec 2015, 4(4): Physical Implementatin Once the simulatin results are justified fr its prper peratin f the system, the physical implementatin f the system is perfrmed as indicated in Figure 11. After sldering each cmpnent based n the circuit design, the resulting autmated digital cntrl bard as it s shwn in figure belw, the micrcntrller is interfaced with the LCD and the relays thrugh dides and then transistrs and als with external crystal scillatr, DC vltage surce, and analg temperature sensr t get the desired utput. The PIC16F877A micrcntrller accepts external signal as an input +5V DC, 16MHz Clck frequency thrugh pin OSC1 (CLKIN) and analg temperature thrugh prt-a (RA0/AN0) in rder t prduce utput signal thrugh prt B and D, i.e., the LCD is cnnected t the PIC pin RB0 RB2 and RD0 RD7; the three transistrs are als cnnected t the PIC via pin RB3 RB5. The status f each cnditin is then displayed thrugh the LCD based n ASCII standard. On the ther hand, the utput f the micrcntrller which directs the respective fan, cmpressr, and heater in rder t regulate the van air cnditin f the truck. This utput is checked in ur digital bard by assigning three LEDs fr each respective fan, cmpressr, and heater. The digital cntrlling bard has als reserved scket (Plug) t cnnect with the refrigeratr truck s electrical and mechanical cntrlling units, i.e., fan, cmpressr, and heater cntrlling bards. Figure 11: Physical implementatin f the system CONCLUSIONS Refrigeratr truck has an aluminum shielded van which is used t transprt easily perishable and temperature sensitive materials frm place t place. In rder t make the temperature balanced and stable, mst f the refrigeratr trucks, starting frm their inventin till present have mainly cling related cntrlling mechanism. By using easily affrdable electrnics cmpnents PIC16F877A chip, LCD, relays, transistrs, capacitrs, resistrs, dides, and pwer supply and suitable prgramming cde written in C prgramming language; an autmated digital cntrller fr refrigeratr truck is designed, simulated and implemented. The cntrller cntrls the air cnditin f the truck s van by prcessing the three states predefined using temperature range, i.e., belw 2 C, between 2 and 6 C and abve 6 C and then directs the respective fan, heater and cmpressr t turn ON/OFF. In this prject the simulatin result is cnfirmed with the physical implementatin result fr its crrectness. Hwever, this digital cntrlling system is prperly wrking and useful when implemented as it is; it might als be pssible t manage remtely by using remte sensing, cmmunicatin and ther relevant technlgies. Cnflict f Interest Authrs declared n cnflict f interest. REFERENCES Matthys, R.J. (1992). Crystal Oscillatr Circuits: Krieger Publishing C, Malabar-Flrida, Revised editin. S.W.Ams, M.R.James, (1959). Principles f Transistr Circuits, Published by Life Bks Ltd. Sxma Technlgies, [Available: ttp:// eprject.cm/abstracts/set-331.%20micr%20cntrller %20based%20refrigeratin%20cntrl%20system.pdf Tassu, S.A., De-Lille., Lewis, J. (2006). Fd Transprt Refrigeratin. Centre fr Energy and Built Envirnment Research. Schl f Engineering and Design, Brunel University. Thein Thein Se., Kyaw Se Lwin., Zaw Min Naing., Aung Se Khaing (2014). Design and Develpment f Micrcntrller Based Air Cnditining System. Internatinal jurnal f Scientific Engineering and Technlgy Research 3(10): Wikipedia (2015). Histry f Refrigeratr truck, [Available: 137