Role of surface radiation on the functionality of thermoelectric cooler with heat sink Anjan Sarkar a, * , Swarup K. Mahapatra b a AMETEK Instruments, Bangalore, India b School of Mechanical Sciences, IIT Bhubaneswar, India highlights  Nowhere the performance of TEC has been evaluated considering the heat sink to be emitting thermal radiation.  There is a shift in the operating points of the TEC for all level of currents when radiation is considered.  The non-functional zone comes closer to the operating zone for radiation for the second working temperature range. article info Article history: Received 21 December 2013 Accepted 12 April 2014 Available online 26 April 2014 Keywords: Thermoelectric cooler Heat sink Thermal radiation Coefficient of performance abstract The present investigation substantiates the inclusion of radiation heat transfer coming from heat sink while modelling the thermal performance of a thermo-electric cooler (TEC). A commercial grade ther- moelectric cooler from Laird Technology and a heat sink from Aavid Thermal Alloy are chosen to perform this study and their actual values revealed by the respective company datasheets have been considered for the comparison. The results provided in the company datasheets are based on the assumption that the heat sink is mounted on the TEC and is cooled by natural convection only. Therefore, the present study conducted in this work, also identifies the heat transfer solely due to natural convection. The results are validated against the available operational company datasheets. Subsequently, the effect of surface radiation from the heat sink in addition to the natural convection on the thermal performance of TEC has been investigated. Furthermore, to bring more clarity in the investigation, two different ranges of working temperatures have been opted and shift in the operational points because of radiation in both ranges have been delineated through data tables, figures and comparative plots. Ó 2014 Elsevier Ltd. All rights reserved. 1. Introduction In spite of high cost and poor power efficiency, thermoelectric cooling is appreciated as it is considered to be an environment friendly refrigeration technology i.e. “Green refrigeration technol- ogy” for small scale localized cooling applications such as in com- puters, infrared detectors, electronics and optoelectronics applications. A thermoelectric refrigerator is a solid-state active cooler which transfers heat from the cold junction to the hot junction connected by two different semiconductor materials continuously being actuated by the direction of the current (widely known as Peltier effect). Relevant few literatures have been referred in this context and are discussed in the following. Yang et al. [1] have described the transient response of TEC with and without mass load through examination of both the minimum temperature reached and the time constant involved in the cooling and recovering stages. Chang et al. [2] investigated that the total thermal resistance of the ther- moelectric cooler (R TEC ) increases with heat load and decreases with input current, whereas thermal resistance in the heat sink (R hs ) increases with input current and decreases with heat load. In their study, they further evaluated the overall resistance (i.e. R t ¼ R TEC þ R hs ) under every heating power and input current. Due to contrary trends of R TEC and R hs for input current, they could find an existence of optimal input current for each R t . Huang and Duang [3] theoretically have solved a linear dynamic model of the ther- moelectric cooler including the heat sink and the cooling load heat exchanger using small signal linearization method. Yushanov et al [4] have numerically solved the governing equations related to the * Corresponding author. Tel.: þ918067159714. E-mail addresses: anjan.sarkar@ametek.com, anjansirkar@gmail.com (A. Sarkar). Contents lists available at ScienceDirect Applied Thermal Engineering journal homepage: www.elsevier.com/locate/apthermeng http://dx.doi.org/10.1016/j.applthermaleng.2014.04.025 1359-4311/Ó 2014 Elsevier Ltd. All rights reserved. Applied Thermal Engineering 69 (2014) 39e45