Study on Single- and Multi-Stage Adsorption Cooling Cycles Working at Sub and Above Atmospheric Conditions

2008 ◽  
Author(s):  
Bidyut B. Saha ◽  
Ibrahim I. El-Sharkawy ◽  
Anutosh Chakraborty ◽  
Shigeru Koyama ◽  
Kim Choon Ng
Keyword(s):  
Activated Carbon ◽  
Atmospheric Pressure ◽  
Activated Carbon Fiber ◽  
Coefficient Of Performance ◽  
Atmospheric Conditions ◽  
Surface Cooling ◽  
Multi Stage ◽  
Theoretical Results ◽  
Partial Vacuum ◽  
Adsorption Cycle

This study deals with the performance analysis of single- and multi-stage adsorption cooling cycles working at partial vacuum and pressurized conditions for cooling applications. Four adsorbent-refrigerant pairs namely activated carbon fiber-ethanol, silica gel-water, Maxsorb II-R134a and Fluka-R134a pairs have been investigated. The former two pairs are deemed to be suitable for adsorption cycles working at pressures ranging from 1 to 11 kPa while the latter two are suitable for those working at above atmospheric pressure conditions typically between about 0.3 and 0.8 MPa. Invoking the adsorption isotherms of the assorted pairs, the pressure-temperature-concentration (P-T-W) diagrams have been presented. Pertaining a thermodynamic framework, the performance of both single- and multi-stage cycles in terms of specific cooling effect (SCE) and coefficient of performance (COP) has also been studied. Theoretical results show that the former two pairs i.e., the adsorption cycles working at partial vacuum pressures are suitable for surface cooling while latter two are suitable for micro cooling applications. Moreover, the multi-stage adsorption cycles can be operational at a heat source temperature below about 55°C, a region that could not be reached by any conventional adsorption cycle.

Modification of activated carbon fiber pore structure by coke deposition

2001 ◽  
Vol 11 (PR3) ◽  
pp. Pr3-279-Pr3-286
Author(s):  
X. Dabou ◽  
P. Samaras ◽  
G. P. Sakellaropoulos
Keyword(s):  
Activated Carbon ◽  
Carbon Fiber ◽  
Pore Structure ◽  
Activated Carbon Fiber ◽  
Coke Deposition

scholarly journals Research on Double-Stage and Multi-Stage Capacitive Deionization Absorption Air-Conditioning System

Processes ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 395
Author(s):  
Feng Cheng ◽  
Boqing Ding ◽  
Xiuwei Li
Keyword(s):  
Air Conditioning ◽  
Pure Water ◽  
Good Choice ◽  
Coefficient Of Performance ◽  
Capacitive Deionization ◽  
Joint Work ◽  
Thermal Regeneration ◽  
Air Conditioning System ◽  
Multi Stage ◽  
Stage System

An absorption air-conditioning system is a good choice for green buildings. It has the superiority in the utilization of renewable energy and the refrigerant is environment-friendly. However, the performance of the traditional absorption system has been restricted by the energy waste in the thermal regeneration process. Capacitive deionization (CDI) regeneration is proposed as a potential method to improve system efficiency. In the new method-based air-conditioning system, strong absorbent solutions and pure water are acquired with the joint work of two CDI units. Nevertheless, the practical CDI device is composed of a lot of CDI units, which is quite different from the theoretical model. To reveal the performance of multiple CDI units, the model of the double/multi-stage CDI system has been developed. Analysis has been made to expose the influence of some key parameters. The results show the double-stage system has better performance than the single-stage system under certain conditions. The coefficient of performance (COP) could exceed 4.5, which is higher than the traditional thermal energy-driven system, or even as competitive as the vapor compression system. More stages with proper voltage distribution better the performance. It also provides the optimization method for the multi-stage CDI system.

Activated carbon fiber felt and polymer fiber as biofilm carrier in a modified University of Cape Town process for sewage treatment

2013 ◽  
Vol 68 (5) ◽  
pp. 1151-1157 ◽  
Author(s):  
Dongkai Zhou
Keyword(s):  
Activated Carbon ◽  
Carbon Fiber ◽  
Inner Core ◽  
Sewage Treatment ◽  
Cape Town ◽  
Activated Carbon Fiber ◽  
Operational Parameters ◽  
Biofilm Carrier ◽  
Carbon Fiber Felt ◽  
University Of Cape Town

Biofilms on fiber-based carriers have attracted much concern in wastewater treatment processes recently. In this study: (1) a novel sandwich structure fiber-based biofilm carrier was produced, which consisted of an inner core composed of polyacrylonitrile-based activated carbon fiber felt (PAN-ACFF) and an outer coat made of polyester reticular cloth with polypropylene fiber loops; (2) the novel carrier was filled in a step-feeding pilot-scale modified University of Cape Town process (MUCT) for sewage treatment; the MUCT contained a series of pre-anoxic/anaerobic/anoxic-1/anoxic-2/oxic tanks, wherein nitrification liquor was recycled to the anoxic-2 tank and an extra liquor return from the anoxic-1 to the pre-anoxic tank was set up; and (3) the removal efficiencies of chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP) were continuously tested for two periods as operational parameters alternated. The optimum values were collected in Period II, when the influent loads were 2,100.6 ± 120.3 gCOD/(d m3), 205.5 ± 20.4 gTN/(d m3), 39.9 ± 3.9 gTP/(d m3), the removal percentages were 93.1 ± 1.1% of COD, 39.4 ± 3.5% of TN, and 84.6 ± 3.4% of TP. For COD, NH4+-N, and TP, the specific removal loads of filler were 291.5 ± 18.2, 22.9 ± 3.1, 4.8 ± 0.5 (g d)/kg.

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