Fast thermal modeling of liquid, thermoelectric, and hybrid cooling

Abstract

Localized hot spots result in elevated on-chip temperatures, significantly limiting the performance, energy efficiency and reliability of today's processors. For efficient removal of hot spots, using superlattice-based thermoelectric coolers (TECs) in cooperation with microchannel liquid cooling has recently been explored. For the design and evaluation of such hybrid cooling solutions, fast and accurate modeling is essential. In this paper, we present a modeling methodology to account for the complex thermal behavior of TECs and liquid microchannels using compact thermal modeling (CTM). CTM provides a desirable tradeoff between accuracy and speed; thus, it is usually preferred over computationally heavy multi-physics simulations when designing and evaluating thermal management techniques. In this paper, we first describe how to jointly model liquid microchannels and TECs for a hybrid cooling design. We then validate the accuracy of our models by comparing the temperatures obtained from them against the temperatures from COMSOL and 3D-ICE. In comparison to COMSOL, the proposed model provides an average error of 2.07 °C for TECs and 0.36 °C for liquid microchannels, while providing four orders of magnitude faster simulation time. Compared to 3D-ICE, the proposed liquid cooling model achieves 0.02 °C average error. We point out challenges related to integrating a new cooling model into an existing compact thermal simulator and show that modeling decisions can affect the reported temperature by up to 20 °C. We conclude our paper by demonstrating an example use case of our proposed model, where we compare the cooling performance of a hybrid cooling design involving microchannels and TECs against a design that adopts liquid cooling only.