Investigation of the Effect of a Synthetic Jet on the Heat Transfer Coefficient PETRA DANCOVA, TOMAS VIT, JAN NOVOSAD Department of Power Engineering Equipment Technical University of Liberec Studentska 2, 46117 Liberec 1 CZECH REPUBLIC petra.dancova@tul.cz Abstract: This paper deals with the experimental investigation of heat transfer coefficient (HTC) and continues authors’ previous research in a paper [1]. HTC is measured with using the thermoanemometry method on a heated plate on which impacts a synthetic jet. Those results are compared with HTC caused by impacted flow from a continual nozzle. The thermoanemometer works in a constant temperature mode for both cases of experiments, and a glue film probe placed on the heated wall is used as a measuring sensor. Key-Words: Synthetic jet, actuator, continual nozzle, heated plate, experiment, thermoanemometry, heat transfer, Nusselt number 1 Introduction A phenomenon of heat transfer is intensively solved in these days. Especially cooling of electronics and micro-electronics devices is the important task. Each electronic device generates heat which grows proportionally with the number of components in a circuit. For the correct operation of the electronic devices, this heat has to be removed, the device should be cooled respectively. Cooling can be done in different ways, e.g.: Passive coolers, they are designed with large surface (in form of lamellas, ribs or rods) and made from materials which are well to conductive heat (cooper, aluminum, etc.), [2]. Active coolers like fans generate the fluid flow from the environment. Very effective is the combination of active and passive coolers, [2]. Liquid cooling is a closed system with flowing heat exchange medium (most often distilled water or water modified to be non-electrically conductive, or in extreme cases a liquid operated at low temperatures such as liquid nitrogen or carbon dioxide). The circuit usually consists of a pump, individual coolers for chilled components and a large passive cooler (so-called "radiator"), [2]. Heat pipe is a hermetically sealed tube with the working substance (water, alcohol, propane butane, Freon, etc.) in form of a small amount of liquid substance and the rest of the tube is filled with its vapors. These heat pipes can transfer large heat outputs while maintaining a small temperature difference (typically around 2 °C). Heat transfer is based on evaporation and condensation, [3]. Peltier cells, i.e. thermoelectric cells which use the Peltier effect. The Peltier cell consists of two semiconductor bodies and a connecting bridge, which provide both power supply and absorption and radiating heat. Peltier cells are usually connected in series in larger units, the so-called cooling thermo-batteries. The advantage of Peltier thermo-batteries is the concentration of cooling or heating effect on a very small area and this area cooling is uniform, [4]. An alternative of cooling in micro-electronic systems can be the application of synthetic jets. In micro-dimensions the flow is often laminar; therefore the heat transfer is small. Synthetic jets could be designed to disturb this laminar flow and intensify heat transfer, [5, 6]. Synthetic jets are often vectored perpendicularly to the surface to generate so-called impact flow, [7, 8]. The heat transfer is in most cases investigated indirectly using the heat and mass transfer analogy: mass transfer is measured and obtained data are recalculated to heat transfer using the ratio Nu Sh ൗ ൌ ൫ Pr Sc ൗ ൯ ୬ , when Nu, Sh, Pr, and Sc is Nusselt, Sherwood, Prandtl, and Schmidt number, respectively. Exponent n in in range (0.33-0.42), [9]. Mass transfer can be obtained e.g. from the naphthalene sublimation, summarizing study can be found in [9]. Petra Dancova et al. International Journal of Mathematical and Computational Methods http://www.iaras.org/iaras/journals/ijmcm ISSN: 2367-895X 315 Volume 2, 2017