Modeling Joule Heating Effect on Thermal Efficiency of Photovoltaic Thermal (PVT) Collectors with Operation Mode Factor (OMF)

The purpose of the present study is developing the operation mode factor (OMF) by remodeling the thermal efficiency model of a hybrid PVT collector during steady state. Joule heating occurs when the photovoltaic (PV) panel operates at a high current during maximum power point tracking (MPPT) on higher irradiation. Under these conditions, some electrical energy converts to thermal energy within the PV cells. Joule heating contributed to increasing the PVT thermal efficiency. The steps were to construct the OMF by remodeling the thermal efficiency involving the Joule heating effect and to validate the results using the model by comparing the simulation and experiment. The dimensionless OMF was responsible for changes in thermal efficiency for PVT-mode. The conductive heat transfer coefficient from the surface to the absorber was the most decisive component in the OMF. Heat removal factor and OMF might be interrelated at the mass flow rate by decreasing PV temperature to maintain Joule heating. The proposed model with OMF had explained PVT-mode and T-mode with the RMS value of less than 1%. This model complemented the results of the previous studies. The results may contribute from the initial design to the operational monitoring for thermal to electrical energy production.

Numerical Prediction of Joule Heating Effect in Electric Hot Incremental Sheet Forming

Since the deformation region involves the interaction of electric-thermal-force coupling in electric hot incremental sheet forming, the numerical simulation of the forming process is unusually difficult. Currently, the thermal-force coupling method is adopted to simulate approximately the whole forming process, and the Joule heating effect is often ignored. Therefore, the numerical simulation of Joule heating effect is especially significant for the prediction accuracy of forming process. In this paper, a novel numerical simulation method, considering electric-thermal-force parameters, was proposed to instantly update the thermal-force condition of forming region. Meanwhile, the model of contact thermal conductance was established combining geometrical and electric-thermal parameters, and then a high-precision finite element model was obtained to predict the Joule heating effect of forming region. In addition to this, the effect of thermal superposition on forming temperature was further analyzed and a modified model of contact thermal conductance was established in electric hot incremental sheet forming.

Flow control in microfluidics devices: electro-osmotic Couette flow with joule heating effect

PurposeJoule heating effect is a pervasive phenomenon in electro-osmotic flow because of the applied electric field and fluid electrical resistivity across the microchannels. Its effect in electro-osmotic flow field is an important mechanism to control the flow inside the microchannels and it includes numerous applications.Design/methodology/approachThis research article details the numerical investigation on alterations in the profile of stream wise velocity of simple Couette-electroosmotic flow and pressure driven electro-osmotic Couette flow by the dynamic viscosity variations happened due to the Joule heating effect throughout the dielectric fluid usually observed in various microfluidic devices.FindingsThe advantages of the Joule heating effect are not only to control the velocity in microchannels but also to act as an active method to enhance the mixing efficiency. The results of numerical investigations reveal that the thermal field due to Joule heating effect causes considerable variation of dynamic viscosity across the microchannel to initiate a shear flow when EDL (Electrical Double Layer) thickness is increased and is being varied across the channel.Originality/valueThis research work suggest how joule heating can be used as en effective mechanism for flow control in microfluidic devices.