Monte Carlo simulation of ammonia adsorption in high-silica zeolites for refrigeration applications

Climate change and the continual rise in cooling demand means more efficient and environmentally friendly refrigeration technologies are required more than ever. One attractive route to reducing future demand is to improve adsorption refrigeration technologies based on natural refrigerants such as ammonia. The choice of ammonia adsorbent plays an important role in achieving improved refrigeration efficiency and suitable operating conditions. This paper reports a detailed study on the suitability of zeolites as an adsorbent of ammonia in refrigeration applications. Systematic Monte Carlo simulations were conducted to study ammonia adsorption in five high-silica zeolites with a wide range of pores sizes and porosities. Simulations were carried out at temperatures between -50 and 50 degrees C and pressures up to 4.0 bar. It is found that zeolites, in particular the ones with large porosities, could be very good ammonia adsorbents for adsorption refrigeration applications, since their use allows for large refrigeration capacities and tuneable operating conditions with good coefficients of performance (COP).