Colossal Barocaloric Effect of Binary Fatty Acid Methyl Esters under Low Pressures near Room Temperature

Refrigeration technology based on the caloric effect is one of the more environmentally friendly alternatives to gas compression refrigeration. The barocaloric effect utilizes pressure to induce phase transition and results in a large entropy change. In this work, a colossal barocaloric effect in the liquid-solid transition (L-S-T) of binary fatty acid methyl esters (BFAMEs) was discovered. At 295 K, an isothermal entropy change as high as 591 J kg^-1 K^-1 and a reversible entropy change of 356 J kg^-1 K^-1 at a hydrostatic pressure of 80 MPa were obtained by mixing methyl palmitate and methyl stearate with a specific ratio to synthesize a BFAME. The value of the isothermal entropy change of the BFAME is comparable to that of a commercial gas compression refrigerant, R134a. This work will provide a new L-S-T candidate material to replace commercial refrigerants for the potential application of caloric effect refrigeration technology.