Distributed and self-adaptive microfluidic cell cooling for CPV dense array receivers

Abstract

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.

Impact of DC-DC Converters on the Energy Performance of a Dense Concentrator PV Array under Nonuniform Irradiance and Temperature Profiles

“…The cooling system (Figure 1) is based on an array of microfluidic cells (dimensions 1.2 mm × 2.0 mm each) with a thermally activated microvalve in each cell, which tailor the coolant flow rate to the needed heat extraction capacity, avoiding overcooling and improving the temperature uniformity [19]. The main advantage of this cooling scheme is that it allows us to determine the working temperature as a function of the energy received by each thermal cell, as it decouples the temperature of each point of the receiver from its position, contrarily to microchannel coolers, where the points at the end of each channel have, along the flow path direction, a higher temperature than those at the beginning.…”

“…This radiation pattern was selected for the comparative study of the 5 electrical configurations, because it presents one of the highest percentages of discrepancy losses of the 6 scenarios shown in Figure 2. The temperature profiles (Figure 2) are determined [35] by considering the cooling system of an array of microfluidic cells with thermally activated microvalves achieving a temperature oscillation between 343.6 and 365.6 K. The cooling system (Figure 1) is based on an array of microfluidic cells (dimensions 1.2 mm × 2.0 mm each) with a thermally activated microvalve in each cell, which tailor the coolant flow rate to the needed heat extraction capacity, avoiding overcooling and improving the temperature uniformity [19]. The main advantage of this cooling scheme is that it allows us to determine the working temperature as a function of the energy received by each thermal cell, as it decouples the temperature of each point of the receiver from its position, contrarily to microchannel coolers, where the points at the end of each channel have, along the flow path direction, a higher temperature than those at the beginning.…”

“…They demonstrated that this type of cooling device was able to generate a temperature dispersion, quantified as the standard deviation of the temperature, lower than 0.7 K across the entire CPV receiver. Laguna et al [18,19] presented a cooling technology based on an array of microfluidic cells with individual thermostatic valves that tailors the flow rate at each cooling cell to reduce temperature nonuniformities and required pumping power, which increased the reliability of the system and the PV production. Yishuang et al [20] compared three typical CPV cooling methods based on air, water and heat pipe cooling.…”

Thermal Analysis of a MEMS-Based Self-Adaptive Microfluidic Cooling Device

“…Barrau et al [ 3 , 4 , 5 ] and Rubio Jimenez et al [ 6 ] proposed different ways of reaching more uniform temperatures of heated zones by using a hybrid jet impingement/micro-channel cooling device and a micro-pin fin heat sink with variable fin density. Along this line, a cooling scheme consisting of an array of microfluidic cells with adaptive valves capable of maintaining a surface temperature below a critical point by locally modulating flow rate in response to changes in heat load, was investigated by [ 7 , 8 , 9 ]. The concept of self-adaptive valve was previously assessed by McCarthy et al [ 10 ], and the authors demonstrated that the mechanism of thermal buckling in a clamped beam fabricated over a slot was able to modulate the flow rate as a function of the valve temperature.…”

“…and Rubio Jimenez et al [6] proposed different ways of reaching more uniform temperatures of heated zones by using a hybrid jet impingement/micro-channel cooling device and a micro-pin fin heat sink with variable fin density. Along this line, a cooling scheme consisting of an array of microfluidic cells with adaptive valves capable of maintaining a surface temperature below a critical point by locally modulating flow rate in response to changes in heat load, was investigated by [7][8][9].…”