Polymeric heat exchangers to increase the COP values of adsorption heat pumps utilizing zeolite coatings

The effects of using polymeric (e.g., PTFE) heat exchanger tubes in adsorption heat pumps employing zeolite coatings were investigated. The power and COP values of these devices were determined by using a previously developed mathematical model and thermodynamic relationships, respectively. For the conditions investigated in this study, it was determined that the power of the adsorption heat pumps remains almost unchanged with respect to the case utilizing stainless steel heat exchanger tubes for the relatively thinner walls of the tubes (approximately <1 mm). The COP values, on the other hand, increased quite significantly when polymeric heat exchanger tubes were used in the adsorption heat pumps, due to the lower mass of the heat exchangers. For the wall thicknesses investigated, the enhancement in the COP values amounted to about 1.5–2.5 folds for the employment of relatively thinner zeolite coatings (5–100 μm).