Mutsuhiro Ito

Improvement of both adsorption performance of silica gel and heat transfer characteristics by means of heat exchange modulation for a heat pump

In order to provide high performance silica gel for an adsorption heat pump (AHP), gels were synthesized using the sol-gel process modified with a new method of controlling the primary gel particle growth by the addition of aluminum ion. In this process, the pores of the silica gel synthesized became smaller when aluminum ion was added in the washing process. Furthermore, this silica gel adsorbed more water at a low region of water vapor pressure and its adsorption ability did not change after 100 repetitive times of adsorping/desorping water vapor. The experimental results from the water vapor adsorption on the silica gel agreed well with theoretical results obtained under the Lump model for heat transfer and intraparticle diffusion model for mass transfer. A new direct heat exchange silica gel module (DS-module) for the AHP was provided, and the heat transfer characteristics during the operation for the adsorption of water vapor were both experimentally and theoretically determined. The period of the adsorption for the DS-module was shorter than that for a silica gel/tube module. Therefore, with the addition of the DS-module the heat transfer in the AHP adsorber was sufficiently enhanced and the maximum heat generation power for the 2-mm-thick DS-module was obtained.

Heat and mass transfer in super active carbon/ethanol adsorption heat pump with a packed bed type adsorber

The possibility of producing cold heat energy by a super active carbon/ethanol adsorption heat pump (AHP) with a packed bed type adsorber is discussed on the basis of both experimental and calculated results of the transient behavior accompanied by this operation. The trend in experimental results for heat and mass transfer agrees well with computer simulation for closed-system, one-component, non-isothermal conditions in both the adsorption and desorption processes. The super active carbon/ethanol AHP proposed generates a high level of cold heat energy by raising the desorption temperature. Therefore, this AHP is applicable to a refrigerator. However, it is suggested that enhancement of heat transfer in the adsorber is indispensable to obtain a high power from this type of AHP.

Cold energy generation characteristics of an adsorption heat pump using a direct heat exchange module

Heat and mass transfer processes in an adsorption heat pump (AHP) using a direct heat exchange module (DS-module) of silica gel were experimentally studied and compared with those for an AHP with a multiple adsorbent tube (MAT) type adsorber. Ultimate heat transfer enhancement for an adsorber of the AHP was almost achieved by using the DS-module and the possibility of its application to a refrigerator for producing low-temperature cold heat energy was proposed.

Study of Heat Transfer Characteristics of MAT-type Adsorber for Adsorption Heat Pump

The heat transfer enhancement of an adsorber of AHP(Adsorption Heat Pump) is discussed introducing a new adsorber of a multiple adsorbent/tube (MAT) type. The observed period of the adsorption/desorption cycle for the AHP with the MAT-type adsorber was much shorter than the packed bed type. The trend of experimental results agreed well with the computer simulation under closed-system, one-component, non-isotherm conditions.