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In this paper, the heat transfer characteristics of multiple pairs of vortex generators (VG) mounted on vertical plate fins of plate fin heat sink (PFHS) are evaluated using computational fluid dynamic simulations. The delta winglet pairs are used as longitudinal VGs, and they are mounted one after the other in the axial direction. Critical design parameters for the double pair of VGs (DPVGs) are identified, and a design of experiment-based simulations is carried out to develop a response surface model for Nusselt number and thermal hydraulic performance parameter. Results show winglet length is a critical design parameter compared with winglet height, and the axial inter VG distance between VG pairs plays a crucial role in improving the heat transfer characteristics. The optimum inter VG distance for a double pair of VG is evaluated, and it is 2.2 to 3 times the length of the delta-winglet. Thermal hydraulic performance of PFHS with double pair of VG is 1.49 times higher than that of plain PFHS. Finally, the variation of heat transfer characteristics against velocity is also evaluated for the PFHS with a DPVG. [ABSTRACT FROM AUTHOR]

The article studies the possibility of using the LabVIEW programming environment to develop real-time dynamic models of continuous processes. The principle of data flow implemented in the LabVIEW environment makes it possible to abandon the direct solution of differential equations when developing a dynamic simulation of a technological object. It is proposed to present the simulation object as a set of dynamic elements, the main of which is the integrating element. The block diagrams of the proportional, integrating, inertial, and delay elements are given. The applicability of the LabVIEW platform for modeling continuous processes is demonstrated on the example of a simple heat exchanger model, which hydrodynamic flows structure corresponds to the ideal mixing model. The schematic and block diagrams of the developed model are given. In order to test the heat exchanger model, a numerical experiment was carried out in static and dynamic modes. The results of testing of the model confirmed its consistency, sensitivity and validity, which are signs of adequacy. [ABSTRACT FROM AUTHOR]

The temperature control loop of the actuating air following the heat exchanger is considered. The control loop consists of a heat exchanger, adjustable air intake, circulation fan, temperature sensor, and temperature controller. A dynamic model of the control loop that takes into account the automatic control system is created. Transient processes that arise in the control loop as a consequence of variations of the altitude of the aircraft are considered. Results of the variation in the actuating air temperature at a temperature control point are obtained. Partial optimization of the coefficients of the controller is performed. Optimal coefficients of the controller are selected. [ABSTRACT FROM AUTHOR]

Dynamic performance simulation of a CFB boiler in a commercial-scale power plant is reported. The boiler system was modeled by a finite number of heat exchanger units, which are sub-grouped into the gas-solid circulation loop, the water-steam circulation loop, and the inter-connected heat exchangers blocks of the boiler. This dynamic model is an extension from the previously reported performance simulation model, which was designed to simulate static performance of the same power plant, where heat and mass for each of the heat exchanger units were balanced for the inter-connected heat exchanger network among the fuel combustion system and the water-steam system. Dynamic performance simulation was achieved by calculating the incremental difference from the previous time step, and progressing for the next time step. Additional discretization of the heat exchanger blocks was necessary to accommodate the dynamic response of the water evaporation and natural circulation as well as the transient response of the metal temperature of the heat exchanger elements. Presentation of the simulation modeling is organized into two parts; system configuration of the model plant and the general approach of the simulation are presented along with the transient behavior of the sub-models in Part I. Dynamic sub-models were integrated in terms of the mass flow and the heat transfer for simulating the CFB boiler system. Dynamic simulation for the open loop response was performed to check the integrated system of the water-steam loop and the solid-gas loop of the total boiler system. Simulation of the total boiler system which includes the closed-loop control system blocks is presented in the following Part II. [ABSTRACT FROM AUTHOR]