Wai Soong Loh

Adsorption Parameter and Heat of Adsorption of Activated Carbon/HFC-134a Pair

This article presents the adsorption isotherms of HFC-134a and activated carbon Maxsorb III measured using the constant-volume–variable-pressure method. The adsorption isotherms cover temperature ranges from 293 to 338 K and pressures up to 0.7 MPa. The trends of the experimental isotherms for activated carbon are found to be identical in all cases with previous studies except that the vapor uptake is slightly higher. The adsorption characteristic of the Dubinin–Ashtakov equation has been regressed from the experimental isotherms data and the maximum specific uptake is 2.15 kg of adsorbate adsorbed per kilogram of activated carbon. The heat of adsorption, which is concentration and temperature dependent, has also been extracted from the experiments.

PARAMETRIC STUDIES OF CHARGING AND DISCHARGING IN ADSORBED NATURAL GAS VESSEL USING ACTIVATED CARBON

This paper presents the adsorption isotherm experiment of Methane and Maxsorb III activated carbon that was conducted and analyzed at temperatures from 5 to 55 °C and pressures up to 2.2 MPa in a volumetric apparatus. It is a complementary to the previous efforts by ways of analyzing the importance between charging and discharging rate, temperature increase and reduce of the bed, the heat transfer process, and the cylinder cooling and heating requirements during the charging and discharging of adsorbed natural gas.

A Study on the Kinetics of Propane-Activated Carbon: Theory and Experiments

Experimental kinetics results of propane in Maxsorb III activated carbon is obtained at temperatures of 10°C and 30°C, and pressures up to 800kPa using a magnetic suspension balance. A multi-gradient linear driving force (LDF) approximation is used for adsorbate uptake as a function of time. The LDF mass-transfer-rate coefficients were thus determined. Using this approach, the experimentally derived LDF coefficients based on independently measured kinetic parameters for propane in the activated-carbon bed agree very well with experimental results. The computational efficiency is gained by adopting this extended LDF model.

Transient Modeling of a Lithium Bromide – Water Absorption Chiller

This article presents a thermodynamic framework for a lithium bromide – water absorption chiller, in which a transient model is developed to simulate the operation process. Local energy and mass balance within the main components like absorber, regenerator, condenser, evaporator and solution heat exchanger is respected to investigate the behavior of the chiller. Experimental correlations are used to predict heat transfer of the related working fluids. The cooling water is set to typical cooling tower conditions of tropical countries such as Singapore. The coefficient of performance (COP) is evaluated against a range of heat source temperatures from 75oC to 100oC. The results indicate the operation conditions of the chiller at its maximum COP is 95oC to 100oC.

Adsorption Thermodynamics of Natural Gas Storage onto Pitch-Based Activated Carbons

Publisher Summary This article presents the adsorption characteristics of methane, which is the major component of NG, on two types of pitch-based activated carbons namely Maxsorb III and ACF (A-20) in the temperature ranges from 5 to 65°C and pressures up to 2.5 MPa. Adsorbed natural gas (ANG) has recently become competitive to compressed natural gas (CNG) for storage and transportation purposes with high energy density and at much lower pressure than CNG. The adsorption characteristics of adsorbents are important information for uptake capacity and thermal management of the adsorptive gas storage. Natural gas has potentially become an alternative energy source in many sectors due to the instability in oil markets and the increase in environmental concerns. The substantial reduction of pollutant emissions and clean combustion are main benefits of natural gas, whose main ingredient is methane. It is widely being popular as a transportation fuel because of relatively lower cost than the oil-derived fuels and prevalent availability in many parts of the world.

High-Pressure Adsorption Isotherms of Carbon Dioxide and Methane on Activated Carbon From Low-Grade Coal of Indonesia

ABSTRACT Adsorption isotherms data of methane and carbon dioxide gases on the activated carbons were measured experimentally using a volumetric method with pressure and temperatures ranging from 0 to 3.5 MPa and 27 to 65°C, respectively. Two types of activated carbons, namely, (1) Kalimantan Timur type activated carbon, which is lab-produced from Indonesian low-grade coal and (2) a commercial (Carbotech) activated carbon were used. The adsorption isotherms obtained were found to belong to type 1 of the International Union of Pure and Applied Chemistry classification. The adsorption uptakes for both carbon dioxide and methane on commercial activated carbon are higher than for the Kalimantan Timur activated carbon. This is due to higher Brunauer–Emmet–Teller surface area and pore volume of the former. Langmuir and Tóth isotherm models are correlated to predict the experimental data with acceptable accuracy.

EXPERIMENTAL INVESTIGATIONS OF ADSORBED NATURAL GAS STORAGE SYSTEM WITH ENHANCED THERMAL MANAGEMENT

An adsorbed natural gas (ANG) storage system with internal thermal control, based on fin and tube type heat exchanger is investigated in this study. The adsorbent bed, which consists of Maxsorb III activated carbon packed in between copper fins and tubes, is demonstrated to study the storage capacity and thermal management of the ANG storage system. The cylinder is pressurized up to 35 bar and water is circulated through the tubes during charge process for quick removal of adsorption heat, thus to increase the storage capacity. Similarly, the adsorbent bed is heated up during discharge process to maximize the gas delivery. The current experimental arrangement presented shows higher storage capacity and better thermal management than the adsorbent bed without fin and tube arrangement.