System design and simulation of constant temperature box using semiconductor refrigeration device

Transcription

1 In. J. Compuer Applicaions in Technology, Vol. Sysem design and simulaion of consan emperaure box using semiconducor refrigeraion device Hui Zhang* The School of Insrumen Science and Opo-elecronic Engineering, P.O. Box 1#, Hefei Universiy of Technology, Anhui , China Fax: *Corresponding auhor Kuang-Chao Fan The School of Insrumen Science and Opo-elecronic Engineering, P.O. Box 1#, Hefei Universiy of Technology, Anhui , China and The Deparmen of Mechanical Engineering, Naional Taiwan Universiy, Taipei, China Fax: (02) Jun Wang The School of Insrumen Science and Opo-elecronic Engineering, P.O. Box 1#, Hefei Universiy of Technology, Anhui , China Fax: Absrac: This paper presens he variaion law of emperaure in hree-dimensional space, which is cooled by he refrigeraion provided by he cold side of a semiconducor. The mahemaical model of he emperaure field of he semiconducor refrigeraion device is described, and a numerical sudy on he emperaure profile in a semiconducor refrigeraion device was carried ou using his model. The problems in he presen hermosaed conainers are discussed, he facor influencing curren air organisaion and emperaure field are analysed. The experimenal resuls show ha forced convecion is of benefi o he cold ransfer and o he rise of refrigeraion rae. Keywords: semiconducor refrigeraion; consan emperaure box; mahemaical model; numerical simulaion. Reference o his paper should be made as follows: Zhang, H., Fan, K.C. and Wang, J. (2011) Sysem design and simulaion of consan emperaure box using semiconducor refrigeraion device, In. J. Compuer Applicaions in Technology, Vol. Biographical noes: Hui Zhang received his Bachelor Degree in Auomaion of Indusry, Maser Degree in Applicaions of Compuer and PhD Degree in Precision Insrumen and Machinery from Hefei Universiy of Technology, Hefei, China. He is a Professor in he School of Insrumen Science and Opo-elecronic Engineering a Hefei Universiy of Technology. He is auhor of more han 50 papers published on journals and conference proceedings. His main research ineress include modern measuremen and conrol echnology in insrumenaion. He is currenly sudying on conrol heory and sysem of environmen for Micro/Nano-meer measuremen. Kuang-Chao Fan received he PhD Degree from Universiy of Mancheser Insiue of Science and Technology in UK in He is he Chair Professor of Mechanical Engineering a Naional Taiwan Universiy, and also a Hefei Universiy of Technology. He is he SME Fellow. His research ineress include manufacuring merology, precision machining, and machine ool echnology. He has published more han 100 journal papers and 200 conference papers. Copyrigh 2011 Inderscience Enerprises Ld.

2 Sysem design and simulaion of consan emperaure box 285 Jun Wang is a Maser candidae in School of Insrumen Science and Opo-elecronic Engineering, Hefei Universiy of Technology. Her main research fields include online measuremen echniques and measuremen auomaion. 1 The principle of numerical simulaion of TEC Thermoelecric Cooler (TEC) modules are high hea-flow devices. The efficiency of semiconducor refrigeraion depends on he emperaure difference beween he cold and ho sides of a hermopile. This emperaure difference can be remarably reduced boh by he hea loss of he enhanced ho side and by he cold dissipaion of he enhanced cold side, hus leading o he rise of semiconducor refrigeraion efficiency. Semiconducor cooling is he applicaion of Pelier effec. When a loop of wo differen conducors passed hrough DC, he emperaure on one side will be very low and on he oher side he emperaure will be high (Deshen, 1993). In his paper, he semiconducor refrigeraion MAA (hp:// which is produced by Melcor corp. is used. I can produce 15 W refrigeraing capaciy wih 12 V power supply. I is fixed as he figure shows. The hea ransfer and air disribuion of he refrigeraion are simulaed when i wors, assuming: he cabine is well blocaded, here is no air release, and he hea conduciviy of he wall is low he air in he cabine is incompressible; is consisency obeys he Boussingesq Hypohesis he airflow in he cabine is urbulen flow he air in he cabine is a ransparen medium, does no paricipae wih radioacive hea ransfer and ignores he radioacive hea ransfer beween he walls. Figure 3 Mesh models (see online version for colours) When here is no hea source in he cabine, pressure disribuion and velociy vecor of middle secion in 3D space. Figure 4 Pressure disribuion (see online version for colours) Figure 1 Insrucion of TEC Figure 5 Velociy vecor (see online version for colours) Figure 2 MAA050T-12 (see online version for colours) When here is one hea resource in he cabine, se 3D urbulen hea ransfer model in he Compuaional Fluid Dynamics (CFD) sofware, define a FAN boundary

3 286 H. Zhang e al. condiion in he cool side and se segregaed solver, 1s-order implici. We can ge node s informaion lie: emperaure, velociy vecor, and pressure, ec. Figure 6 Simulaion resul of TEC: emperaure disribue of mid-surfaces; velociy vecor of mid-surfaces and emperaure disribue of 3D space (see online version for colours) This emperaure difference can be remarably reduced boh by he hea loss of he enhanced ho side and by he cold dissipaion of he enhanced cold side, hus leading o he rise of semiconducor refrigeraion efficiency. The main way o absrac hea include: naural convecion hea ransfer, forced convecion hea ransfer, waer cooling, phase-change hea ransfer, boiling hea ransfer, ec. DC fans can be mouned direcly o MAA050T-12 on boh hea and cold side and provide forced air convecion. 2 Designing of consan emperaure box using TEC Design specificaion of he accuracy of conrolled emperaure is 20 ± 0.05 C; he enire space requires high emperaure uniformiy, and canno appear in any blind area of emperaure or inensive air movemen. The emperaure sabiliy is aained by conrolling he wor curren of semiconducor refrigeraion, and he emperaure uniformiy of he woring place is depending on he mechanical srucure design. In his paper, we use cube srucure wih hree differen caviies, which are: consan emperaure caviy, seadying pressure caviy and refrigeraing caviy. The air ges across he air reurn grille from he boom of consan emperaure caviy o refrigeraing caviy, being cooled and mixed by semiconducor refrigeraion device, hen insufflaed o consan emperaure caviy by AC fan. In he seadying pressure caviy, he air mixed again, hen hrough he orifice plae flowed o he woring place (consan emperaure caviy). By air convecion hea ransfer, le he cool energy, which is produced by he semiconducor refrigeraion device, ransfer o he consan emperaure caviy, ensuring he emperaure sabiliy of woring place. To mae he air disribuion more uniform, we add in a wide-guide board and an orifice plae in he seadying pressure caviy. Wide-guide is a funnel-shaped board; i maes he air evenly disribued in cerain area. When he pressure of seadying pressure caviy is higher han he pressure of consan emperaure caviy, he difference in pressure beween he wo sides of orifice plae maes pison ype air flow below he orifice plae, i maes he air gained o mix sufficienly, wih uniform emperaure and velociy field. We use 80 mm bea glass fibre as hermal insulaion maerial filled surrounding he box. The srucure and picure of he insulaed cabine is shown here. Figure 7 Experimen model (see online version for colours) During seady-sae operaions, he hea ransfer in cabine in which semiconducor refrigeraion is woring is influenced by boh forced convecion and naural convecion.

4 Sysem design and simulaion of consan emperaure box 287 Figure 8 Srucure of cabine 3 Analysis o consan emperaure box using TEC Woring condiion: he insulaed cabine is placed in air condiioning room; he emperaure is invariable a 25 C. The semiconducor refrigeraion device is woring in single direcion. The hea ransfer in cabine in which semiconducor refrigeraion woring is mixed convecion, influenced by boh forced convecion and naural convecion, and he airflow in he cabine is urbulen flow. During seady-sae operaions, he air disribuion is seady flow, bu during he incipien sage of sar-up i was unseady flow. Consisency obeys o Boussingesq Hypohesis. Sudy on mahemaical model for flowing and hea ransferring process, impor ensor labelling mehod, i can be formulaed as: Coninuous equaion: div(u) = 0 Momenum equaion (Navier-Soes equaion): 2 u j ( ρuu i j) = p+ ρ + ( µ + µ ) xi xi 3 xi xi u i + ( µ + µ ) xi xj equaion (Turbulen ineic energy equaion): µ ( ρu i ) = + G ρ xi xi σ xi equaion (Turbulen dissipaion energy equaion): µ ( ρu ) i = + ( cg 1 c2ρ ) xi xi σ xi G he ineic energy generaion iem caused by mean velociy gradien: 2 u u i j ui G = µ +, µ = ρc µ xj x i xj where: ρ p u Fluid densiy Pressure Hea ransfer coefficien Time Velociy vecor Turbulen dissipaion rae Turbulen ineic energy µ Turbulen viscosiy. The empirical parameers: c µ = 0.09, c 1 = 1.44, c 2 = 1.92, σ = 1.0, σ = 1.3. Symbol definiion is according o Wenquan (1986). The principle of hea ransfer enhancemen and field-coordinaed is according o Guo e al. (1998). Convecion hea ransfer is essenially a hea ransfer ha conains an inernal hea source, he flowing of fluid is equivalen o he weigh o hea source; inensiy of convecion hea depends on he inensiy of equivalen hea source, i ress wih he difference in emperaure, velociy of flowing, and hermo-physical propery, ranspor propery of he fluid, and also depends on he angle beween velociy vecor and hea sream vecor. Diminishing he angle will enhance he convecion hea ransfer. The ways of enhancing hea ransfer include: increase Re Number, for example, increase he velociy of flow, decrease he passage diameer, increase he Pr number, and diminish he angle beween velociy vecor and hea sream vecor, ec. We place a wide-guide board and an orifice plae in he insulaed cabine, le he air flows hrough he hea source; mee he demands of diminishing he angle beween velociy vecor and hea sream vecor, so as o enhance he convecion hea ransfer o a cerain exen. 4 Simulaing analysis on consan emperaure box No hea source. The cabine is well blocaded, here is no air release, he hea conduciviy of he wall exiss, and he ambien emperaure is higher han he cabine. Assuming he air in he cabine is incompressible, is consisency obeys he Boussingesq Hypohesis. The air in he cabine is a ransparen medium; i does no paricipae wih radioacive hea ransfer; i ignores he radioacive hea ransfer beween he wall. The cool energy is provided by semiconducor refrigeraion device; he emperaure and velociy of inle can be conrolled.

5 288 H. Zhang e al. Wih he same emperaure of inle air, increase in inle velociy efficiency enhances he convecion hea ransfer, bu Nano-Scale Measuremen require he environmen no o be inensive for air movemen; hus during seady-sae operaions, he velociy of air fluid should below 1 m/s. We can choose a suiable large velociy during he incipien sage of sar-up. Conain hea source. When nano-scale measuremen insulaed cabine woring, he main hea source in he consan emperaure caviy is a piezoelecric moor; he maximum flash emperaure is up o 320 K. Suppose here is a consan hea source, emperaure is 323 K. Increased inle velociy could efficienly abae he influence of hea source; when increased o a cerain degree, i will nearly have no influence o he emperaure field. Bu reducion of he emperaure of inle airflow does no wor obviously. In addiion, we can isolae he hea source and cooling i separaely. Figure 10 Simulaion resul of cabine (inle V = 0.5 m/s, T = 292K) emperaure disribue of mid-surfaces; (coninued) Figure 9 Mesh models of cabine (see online version for colours) Figure 10 Simulaion resul of cabine (inle V = 0.5 m/s, T = 292K) emperaure disribue of mid-surfaces; Figure 11 Simulaion resul of cabine (inle V = 3 m/s, T = 292 K): emperaure disribue of mid-surfaces;

6 Sysem design and simulaion of consan emperaure box 289 Figure 11 Simulaion resul of cabine (inle V = 3 m/s, T = 292 K): emperaure disribue of mid-surfaces; (coninued) Figure 12 Simulaion resul of cabine (inle V = 0.5 m/s, T = 292 K): emperaure disribue of mid-surfaces; (coninued) Figure 12 Simulaion resul of cabine (inle V = 0.5 m/s, T = 292 K): emperaure disribue of mid-surfaces; Figure 13 Simulaion resul of cabine of emperaure disribue of mid-surfaces: inle V = 0.5 m/s, T = 291 K; inle V = 3 m/s, T = 291 K and inle V = 5 m/s, T = 291 K (see online version for colours)

7 290 H. Zhang e al. Figure 13 Simulaion resul of cabine of emperaure disribue of mid-surfaces: inle V = 0.5 m/s, T = 291 K; inle V = 3 m/s, T = 291 K and inle V = 5 m/s, T = 291 K (see online version for colours) (coninued) and is esed under he condiions of he naural and forced convecion in a semiconducor refrigeraion device under seady woring condiions. The mahemaical model of he emperaure field of he semiconducor refrigeraion device is described, and a numerical sudy on he emperaure profile in a semiconducor refrigeraion device was carried ou using his model. The experimenal resuls show ha forced convecion is of benefi o he cold ransfer and o he rise of refrigeraion rae. The DC fans on he semiconducor refrigeraion device and he AC fan in he cabine maes hea sources, i influences he emperaure conrol and drags on he ransiion process The coefficien of hea insulaion of he cabine is no enough The radioacive hea ransfer canno be ignored. Acnowledgemen This research is par of an Inernaional Cooperaion Projec wih Norh Ausralia Universiy and funded by he Naional Naural Science Foundaion of China under conrac number: References Deshen, X. (1993) Thermoelecric Technology and Applicaions [M], Shanghai Jiaoong Universiy Press, Shanghai, China. Guo, Z.Y., Li, D.Y. and Wang, B.X. (1998) A novel concep for convecive hea ransfer enhancemen, In. J. Hea. Mass. Transfer, Vol. 41, pp Wenquan, T. (1986) Numerical Calculaion of Hea Transfer [M], Xi an Jiaoong Universiy Press, Xi an, China. 5 Conclusion This paper presens he law of change in emperaure wih he passing of ime of a space, which is cooled by he refrigeraion provided by he cold side of a semiconducor, Websie hp://