CFD Simulation of Silica Gel as an Adsorbent on Finned Tube Adsorbent Bed

Abstract

The adsorption technology is becoming the more expected solution by today’s researchers for fix the energy and environmental issues. The main part of the cooling system adsorption is adsorbent and adsorbate. One of the most widely used adsorbents in research of adsorption technology is silica gel. A new silica gel-water adsorption chiller design was developed that composed of two sorption chambers with compact fin tube heat exchangers as adsorber, condenser, and evaporator. Energy, mass, and momentum conservation equations of the adsorption systems have been used for the CFD two and three dimensional models. The geometry of simulation is simply made within silica gel layer between two fins. The simulation is also implemented using a finite volume method through the CFD software Fluent. User defined functions are given to modify the energy, mass, and momentum conservation equations. The simulation of adsorption process is adjusted at unsteady condition. Adsorption and desorption processes are simulated with room temperature for cooling water inlet at temperature 305.15 °K, hot water inlet at temperature 353.15 °K, mass flow rate cooling water inlet at 0.3 kg/s and pressure 32 KPa. For the whole adsorbent bed area, the result shows that the highest absolute adsorption rate at the outer surface, while the lowest rate is at the center. After adsorption was finished, the condition is reversed. The highest absolute adsorption rate is achieved at center, while the lowest rate is achieved at the outer surface.

Heat and Mass Transfer Analysis Within a Disc Shaped Fluidized Sorption Reactor

“…▪ low coefficient of performance [17], ▪ large weight & volume [15], ▪ intermittent cooling [18], ▪ high initial procurement cost [18], ▪ exploitation under vacuum conditions [19].…”

Evaluation of Heat Transfer Performance of a Multi-Disc Sorption Bed Dedicated for Adsorption Cooling Technology

“…The adsorbates are natural coolants such as water, ethanol, methanol, CO 2 , or ammonia. These working pairs in adsorption cooling technology are characterized by zero global warming potential (GPW) and ozone depletion potential (ODP) [14].…”

“…Moreover, on the markets of the Middle and the Far East, adsorption technology is intensively developed because of the possibility of desalination of seawater along with the production of cooling energy [17]. But the widespread application of adsorption chillers is limited by the following shortcomings of adsorption cooling technology: low coefficient of performance [18], large weight and volume [16], intermittent cooling [14], high initial procurement cost [14], and exploitation under vacuum conditions [2].…”

“…Enhancing the adsorption kinetics by improving heat and mass transfer is necessary in order to improve the adsorption chiller performance [12]. Both, performance and dimensions of the device are dependent on the design of a heat exchanger constituting the adsorption bed [57,58], which is the most important part of the chiller [14]. That is why the advances in the heat exchanger design will directly contribute to diminishing the drawbacks of these environmentally friendly devices.…”