Moisture thermal battery with autonomous water harvesting for passive electronics cooling
Jian Zeng, Xintong Zhang, Ka Man Chung, Tianshi Feng, Haowen Zhang, Ravi Prasher, Renkun Chen
Abstract
Passive cooling of high-power electronics with minimum energy and water input is critical for the global water-energy nexus but has been challenging because of the large fluctuation in power and heat loads between the on/off-peak hours. Here we develop a moisture thermal battery (MTB) by coating superabsorbent hydrogel onto a pin fin heat sink with a large surface. The MTB leverages large latent heat and high thermal conductance of water evaporation for electronics cooling during on-peak hours and, importantly, autonomously harvests atmospheric moisture and stores the water during off hours. The MTB provides a thermal capacity of up to ∼200 kWh m−2 for evaporative cooling with a record-high effective heat transfer coefficient of up to ∼1,000 W m−2 K−1 for a passive device (no external power). The MTB suppresses the temperature fluctuation of a high-power field effect transistor and a computer CPU between the on- and off-peak hours by ∼15 K.