Phase Change Materials
The heating and cooling of spaces for personal comfort dominates residential electricity usage. This presents a unique opportunity for thermal storage, which has several advantages over batteries including: higher round trip efficiency, the use of lower value energy (waste heat) and potentially lower cost/higher lifetime. However, the static transition temperature of phase change materials (PCMs) drastically limits their utility through seasonal changes - PCMs may be active for as little as 40% of the calendar year depending on the climate. The Liu Lab group is currently exploring electrochemical strategies for dynamically tuning the transition temperature of polymeric PCMs. This work is in collaboration with Ravi Prasher, Chris Dames and Sumanjeet Kaur.
This project aims to construct the design principle for solid to solid phase change material (PCM) possessing both high heat capacity and tunable transition temperature (Tt) as encapsulation-free thermal storage energy materials for sustainable energy usage of heat ventilation air conditioning (HVAC) systems in buildings. The design will be based on a comb-branch polymer which two different design approaches. The first design will be a polymer containing two different domains, crystalline alkyl chain (for heat capacity) and short ethylene oxide chains (for Tt tunability). The second polymer will consist of a single domain of long ethylene oxide chains. The long ethylene oxide branch has shown the potential to provide substantial-high heat capacity as well as Tt tunability (Figure 2).