جستجوی مقالات مرتبط با کلیدواژه « adsorbent bed » در نشریات گروه « مکانیک »

In the present study, adsorbent bed of an adsorption chiller with finned flat-tube heat exchanger has been simulated three dimensionally based on the heat and mass transfer model with finite volume method. To examine the inter-particle mass transfer resistance effects on the system performance parameters, two different configurations of adsorbent bed including rectangular and trapezoidal fins with identical length and adsorbent mass have been considered and the effects of bed length on the system performance for different fin height and fin pitch have been studied. Moreover, effects of bed length for different particle diameters and also heating source temperatures have been investigated. Results indicated that increasing of bed length (or in the other words increasing of inter-particle resistance) increases and decreases cycle time and specific cooling power, respectively, yet the coefficient of performance is not influenced. Also, increasing bed length reduces the difference between specific cooling power of rectangular and trapezoidal beds if there is any. Moreover it is clear that optimum particles size increase with bed length increase. Finally, it is shown that effect of higher heating fluid temperature on specific cooling power improvement for beds with smaller length is more significant than those with longer length.

Adsorption cycle has become one of most popular technologies in recent years which operates based upon the adsorption and desorption of an adsorptive material in an adsorbent material which is usually a porous solid. Thus, a four-bed adsorption cycle with silica gel-water as working pair is modeled by means of a computer code written in MATLAB software, and thermodynamic properties are obtained from REFPROP software. In this article, in order to consider the heat transfer process more accurately and the heat transfer to the environment from the tubes, the passing flow in the adsorbent beds, evaporator, condenser and the connecting pipes between the master and slave beds are discretized. The next step directs to investigate the effect of entrance flow temperature to the adsorbent bed during cooling and heating processes on the operating parameters of system and energy lost. The obtained results indicate that increasing the temperature of hot water and decreasing the temperature of cooling water will lead to the increase of COP and cooling capacity of system. Hence, the best choice based on the maximum available temperature for hot water and normal temperature range for cooling water are 75ᵒC and 25ᵒC, respectively. In these conditions, COP and cooling capacity of system will be 0.37 and 17.2Kw, respectively.

In the present study¡ for the first time¡ adsorbent bed of SWS-1L/water adsorption chiller with rectangular and trapezoidal finned flat-tube heat exchanger with has been simulated three dimensionally based on the distributed parameters model and finite volume method. Effects of some important parameters on the chiller performance such as bed averaged pressure¡ temperature and uptake variations with cycle time have been examined for better understanding of bed dynamic behavior. Also¡ a comparative study between two different configurations of adsorbent bed including rectangular and trapezoidal fins has been conducted based on identical adsorbent mass. For this purpose¡ bed temperature¡ uptake and pressure distributions as well as the vapor flow patterns at the end of heating cycle phases and also effects of fin height and spacing on the system performance have been studied. In this investigation at fixed bed length of 20mm¡ fin height and spacing variations have been examined in the range of 8-20mm and 3-12mm¡ respectively. Results indicated that the system performance with rectangular and trapezoidal adsorbent beds are almost similar except for those conditions which fin spacing is 3mm and fin height are 14¡ 20mm. For the mentioned dimensions¡ the specific cooling power (SCP) of rectangular beds are almost 5% and 17% (for fin heights of 14 and 20mm¡ respectively) better than those of trapezoidal beds. Maximum and minimum SCP of adsorption chiller with flat-tube heat exchanger were obtained about 882 and 163W/kg for the smallest and the largest bed geometry and operating conditions considered in this study.