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Abstract. Temperature non uniformities of the CPV receivers lead to mismatch losses. In order to deal with this issue, a cooling device, formed by a matrix of microfluidic cells with individually variable coolant flow rate, has been developed. This device tailors the distribution of the heat extraction capacity over the CPV receiver to the local cooling needs in order to reduce the temperature non uniformities with respect to microchannel devices when submitted to uniform or non-uniform illumination profiles. At equal average temperature of the CPV receiver, power generation applying the matrix of microfluidic cells with individually variable coolant flow rate is 9.7% higher than the one with conventional microchannel technology.

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This study presents a thermal analysis of a temperature-driven microfluidic cell through a nonlinear self-adaptive micro valve that provides the mechanisms for the system to maintain a given critical temperature in an efficient way. For the description of the dynamics of the microfluidic cell, a system of two ordinary differential equations subjected to a nonlinear boundary condition, which describes the behavior of the valve, is proposed. The solution of the model, for determined conditions, shows the strong nonlinearity between the overall thermal resistance of the device and the heat flux dissipated due to the action of the thermostatic valve, obtaining a variable thermal resistance from 1.6 × 10−5 to 2.0 × 10−4 Km2/W. In addition, a stability analysis of the temperature-driven microfluidic cell is presented. The stability of the device is essential for its proper functioning and thus, to prevent its oscillating behavior. Therefore, this work focuses on assessing the range of design parameters of the self-adaptive micro valve to produce a stable behavior for the entire system. The stability analysis was performed by studying the linear perturbation around the stationary solution, with the model solved for various heat flows, flow rates, and critical temperatures. Finally, a map of the design parameters space, which specifies the region with asymptotic stability, was found. In this map, the critical temperature (temperature at which the valve initiates the buckling) plays and important role.