Model-based control of vapor compression cycles for transient heat-flux removal

Dryout avoidance control for multi-evaporator vapor compression cycle cooling

“…The heated accumulator tank serves to separate the vapor and liquid phases in the suction line, and alter the balance of circulating vapor by boiling the collected saturated liquid using external band-heaters. The cycle thermodynamics are shown in [17]. Alternative methods are available for post-evaporator heating, including internal heat exchangers [12] and secondary low heat flux evaporators [9,12].…”

“…Pressure-enthalpy diagram of a multiple-evaporator vapor compression system for imposed heat flux cooling. Quality lines are shown for the two-phase region [17]. mn;set is provided by the compressor speed x, and distributed using EEV openings Av;n. The EEV are also used to stabilize differential pressure DP, and the compressor and accumulator heat input are used to stabilize evaporator pressure Pe.…”

“…Current strategies for CHF avoidance in active two-phase cooling of electronics include heat-spreaders or cold-plates to enhance heat transfer and lower heat flux [7][8][9][10][11][12][13][14], setting low evaporator outlet quality setpoints to maintain a large CHF safety factor [7,[11][12][13][14], and CHF avoidance control using wall temperature feedback proposed by our group [15][16][17][18]. Several experimental electronics cooling studies that implement these techniques are summarized in Table 1, with representative test section conditions reported.…”

“…The main contribution compared to past CHF avoidance controllers [15][16][17][18] is the inner loop, outer loop control structure where evaporator outlet quality is regulated instead of wall temperature. The outlet quality is more directly linked to CHF through the critical quality, and the controller is formulated to maintain a fixed critical quality margin by throttling mass flow rate.…”

“…Additionally, the proposed proportional-integral (PI) control architecture extends to multiple evaporators, implements feedforward, and offers improved stability over the control in [15,16]. Finally, this approach does not require the detailed model information used in multivariate CHF avoidance controllers [17,18], therefore it is more applicable for cases where model information is lacking. …”