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This experimental study follows on our previous work on the development of robust fuzzy-based thermal control strategies of a multi-room sub-scaled building testbed. In the present analysis, the focus is placed on testing the robustness of the fuzzy controller under internal and external disturbances, as it deals with maintaining specific setpoint values of room temperatures. The testbed has eight rooms, distributed on two floors, with a cooling unit that supplies cool air to each room, and eight 40 W light bulbs serving as heat sources. T-type thermocouples gather the temperature data, and eight dampers deliver the airflow. The controller uses information about the difference between setpoint and actual temperatures, their derivative, and their cumulative integral. The fuzzy sets and if-then rules are built based on experimental data, and a Mamdani inference method is used to provide the inputs to the actuators. Results from experimental tests show that the fuzzy control strategy can handle the different types of disturbances while maintaining the room setpoints. 

This study presents numerical simulations of the convective heat transfer on wavy microchannels to investigate heat transfer enhancement in these systems. The objective is to propose a methodology based on local and global energy balances in the device, instead of the commonly used Nusselt number, as an alternative for the thermal analysis. This investigation is carried out on a single-wave microchannel model of size 0.5 mm by 0.5 mm by 20 mm length, with water flowing inside the channel, exposed to a heat influx of 47 W/cm2 at the bottom. The governing equations for an incompressible laminar flow and conjugate heat transfer are first built, and then solved, for representative models, with copper as the solid-block material under a number of operating conditions (cold-water flowrates of 𝑅𝑒=50, 100, and 150), by the finite element technique. From computed velocity, pressure and temperature fields, local and global energy balances based on cross-section-averaged velocities and temperatures enable calculating the heat rate at each section of the corresponding device. Results from this study for two different designs, namely, serpentine and divergent-convergent layouts, show that this so-called averaged energy-balance methodology enables higher accuracy than that based on Nusselt numbers since neither transfer coefficients nor characteristic temperatures are needed.