Performance of Desiccant wheel for Low Humidity Drying System

Transcription

1 WSEAS RANSACIONS on HEA and MASS RANSFER Performance of Desiccant heel for Lo Humidity Dryg System * RI SUYONO, KAMARUZZAMAN SOPIAN, SOHIF MA, MUHAMMAD YAHYA, MOHD HAFIDZ RUSLAN, MOHD YUSUF SULAIMAN, AZAMI ZAHARIM Solar Energy Research Institute (SERI), Universiti Kebangsaan Malaysia 430 UKM Bangi, Selangor, MALAYSIA. * Correspondent author, tri_suyono78@yahoo.com Abstract: - Dryg is an important process for preservg food and non-food products. Solar desiccant dryg system has been designed and fabricated for the production of dried products. he system has controllable dryg temperature, humidity and flo rate of commercial/dustrial capacity accordance ith the characteristics of the material, so that it is not damaged the dryg process. his system consists of heat pipe evacuated tube, cross flo heat exchanger, desiccant heel, hot ater pump, the hot ater tank, dryg chamber and electrical air heater. Experiments ere conducted ith to modes: () Heat exchanger to heat the air the regeneration process and (2) Heat exchanger to heat the air after the dehumidification process, hile the regeneration process utilized an electrical air heater. Experiment on the desiccant heel of mode () shoed that the average effectiveness of sensible dehumidification, sensible regeneration, latent dehumidification and latent regeneration ere 72.6%, 82.3%, 79.32% and 78.9% respectively. In mode (2), the average effectiveness of sensible dehumidification, sensible regeneration, latent dehumidification and latent regeneration ere 7.4%, 7.99%, 66.97% and 72.8% respectively. Mode () as better than mode (2) ith mean dryg air temperature and absolute humidity ere 58 o C and kg (H2O) /kg (dry air) respectively. he system as able to evaporate 0.8 kg (H2O) /hr of ater the materials at dryg efficiency of %. Keyords: - Desiccant heel, temperature and humidity, ater evaporation. Introduction Depletg of fossil and gas reserves, combed ith the grog concerns of global armg has necessitated an urgent search for alternative energy sources to cater to the present day demands. An alternative energy resource such as solar energy is becomg creasgly attractive. Solar energy is a permanent and environmentally friendly source of reneable energy. One of the most important components of a solar energy system is the solar collector. Solar collectors are key components many engeerg applications. It is can be used for many applications dryg of agricultural products, space heatg, solar desalation, etc. Improvg their performance is essential for commercial acceptance of their use such applications [-5]. Various types of solar dryg systems for agricultural and mare products have been revieed [6]. Solar dryg system is one of the most attractive and promisg applications of solar energy systems tropical and subtropical countries. he technical development of solar dryg systems can proceed to directions. Firstly, simple, lo poer, short life, and comparatively lo efficiencydryg system. Secondly, high efficiency, high poer, long life expensive dryg system [7,8]. Dryg process plays an important role the preservation of agricultural products. Air dryg is the most frequently used dehydration operation the food and chemical dustry. he ide variety of dehydrated foods, hich today are available to consumers and the terestg concern for meetg quality specifications and energy conservation, emphasize the need for a through understandg of the dryg process [9]. Dryg process prciple is to vaporize the ater the dried material. his process is fluenced by temperature, humidity and air velocity dryer. In the process of dryg air required to heat and dry so that dryg time can be shortened, but the air temperature must be adjusted to the properties of dried material. E-ISSN: Issue 4, Volume 7, October 202

2 WSEAS RANSACIONS on HEA and MASS RANSFER Desiccant heel is idely used to loer the humidity of air the coolg system. Desiccant heel has a good ability to absorb ater air [0]. In the process of air through desiccant heel that is latent and sensible state, here addition to the air becomes dry, the air ill also experience an crease temperature [-8]. 2 Dryg System his system consists of heat pipe evacuated tube collectors ith area of 3:32 m 2, cross flo heat exchanger for regeneration and to heat the air after dehumidification, desiccant heel ith model no. 7 WSG produced by NOVELAIRE havg operatg system : and maximum flo rate of.0 cfm, hot ater pump ith maximum capacity of 2 liters/mute, the hot ater tank ith maximum capacity of 230 liter, dryg chamber and electrical air heater for use hen there is no sun or to crease the temperature. he use of desiccant heel for absorbg the moisture the dryer system is appropriate because not only the air becomes drier, but it also becomes hotter due to isotherms process. Performance of the collectors as determed. he ater flo rate of 8 liters/mutes as the optimum flo the dryg process. Experiments ere conducted ith to modes: () Heat exchanger to heat the air the regeneration process and (2) Heat exchanger to heat the air after the dehumidification process, hile the regeneration process utilized an electrical air heater. Flo rate this experiment as made at the cfm /,579.5 m 3 / h for both processes (regeneration and dehumidification), mean ratio beteen the regeneration of the desiccant heel and dehumidification :. Fig. schematic diagram of solar desiccant dryg system mode () Fig.2 schematic diagram of solar desiccant dryg system mode (2) Fig.3 the solar desiccant dryg system 3 Analytical Method his system uses solar energy as heat sources, heat energy from the sun transferred to the ater through the heat pipe evacuated tube. Hot ater floed to the heat exchanger to heat air and ater that has passed through a heat exchanger and the heat flo is reduced to the hot ater tank and then floed back to the collector ith hot ater pump, so this process takes place contuously throughout the process. Hot air generated by the heat exchanger is used for the regeneration desiccant heel and heat the air after the dehumidification process. his paper ill only discuss the performance of desiccant heel and the estimate dryg process, hile the collector performance, heat exchangers and other components not discussed. Desiccant heel operatg system there are to processes, namely the process of regeneration and dehumidification [7]. his process is called regeneration or recovery process is the process of E-ISSN: Issue 4, Volume 7, October 202

3 WSEAS RANSACIONS on HEA and MASS RANSFER dryg silica gel desiccant that has been et hile due process of dehumidification. While the dehumidification process is the process of ater absorption the air so the air ill become drier and the temperature is creased [20]. o determe the desiccant heel performance ill be evaluated effectiveness dehumidification and regeneration process (Sensible and latten), and the adiabatic effectiveness []. 3. Dehumidification Process Sensible/thermal Effectiveness m 2. sbl () mm 7 Latent Effectiveness m 2. ltn (2) mm 7 From the equation above, the temperature and absolute humidity of air hich has passed the dehumidification process can be calculated by the follog equation: m 7 m 2. sbl m m 7 m 2. ltn m (3) (4) 3.2 Regeneration Process Equation for the process of regeneration can be ritten as follos: Sensible / thermal Effectiveness m reg 8 7 reg. sbl (5) mm 7 Latent Effectiveness m 8 7 reg. ltn (6) mm 7 hus the temperature and absolute humidity of air that has passed through the process of regeneration can be ritten ith the follog equation: m 7 7 m reg. out reg. sbl m m 7 7 m reg. out reg. ltn m (7) (8) Adiabatic efficiency can be calculated by the follog equation: ( h2 h ) (2h h2 ) adiabatic (9) h h 3.3 Dryg Estimate In the analysis of the dryg time ill be calculated theoretically ith the assumption that ideal dryg process, and not discuss the nature of the material the dryg process. Decrease ater content the dried material as calculated each 30-mute tervals until the material is dried achieve the desired ater content. In this analysis ill look for reduction ater content the dried material usg pick-up efficiency equation [2]. out W p vt( ) (0) as If, W m o m then, t mo mt p vt( h h ) () t o as m m vt( ) ) (2) as ( as p he decrease the per time period m t. n mo. n ( vt( as ) p) n (3) mc p v G a (4) ( ) ( ) 4. Results and Discussion Overall performance of desiccant heel is strongly fluenced by the air used the process of regeneration and the air that goes to the process of dehumidification. he more hot and dry air that is used process regeneration and air enterg the E-ISSN: Issue 4, Volume 7, October 202

4 dehumidification process, the air generated the dehumidification process ill be more hot and dry because the desiccant heel operation occurs Sensible and latent. Sensible process occurs because the process is valid isoterm process. 4. Dehumidification Process Dehumidification is a process that is expected the use of desiccant heel. dehumidification process is the process of absorption of ater the air by an absorbent material (silica gell) so that the air becomes drier. he air that has passed through this process ill become more dry and creasess of temperature. his process is fluenced by the air used to dry the silica gell (regenration process). Absolute Humidity Sensible Dehumidification WSEAS RANSACIONS on HEA and MASS RANSFER 4.. Dehumidification Process Mode () Dehumidification process on this mode produces the appropriate temperature and humidity for the dryg process. and regeneration process comg ith let air temperature an average ere 33.9 o C and 67 o C ill result air temperature of 58 C, this process can be seen figure 20. Experiment results sho that the dehumidification process the same conditions produce air temperature of 58 o C, this dicates that the results approached theritic and experiment, the results can be seen Figure 4. Sensible effectiveness of this system an average of 73% is shon Figure 5. Absolute humidity at the let air regeneration and dehumidification process ere kg H2O /kg dry.air and 4 kg H2O /kg dry.air respectively, ill result absolute humidity of air theoretic and experiment ere 0.07 kg H2O /kg dry.air and kg H2O /kg dry.air respectively. From the results of these experiments is knon latent effectiveness this mode an average of 79.3%. his process can be seen Figure 6 and 7. emperature ( o C) Fig.4 and experimental sensible dehumidification Fig.5 dehumidification sensible effectiveness Latent Dehumidification Fig.6 theoretical and experimental latent dehumidification Fig.7 Dehumidification Latent Effectiveness 4..2 Dehumidification Process Mode (2) In the mode (2) this air is used for the regeneration process is heated ith electrical air heater. Dehumidification and regeneration process comg ith let air temperature an average ere 34 o C and 48 o C ill result air temperature of C, this process can be seen figure 22. Experiment results sho that the dehumidification process the same conditions produce air temperature of 44.5 o C, E-ISSN: Issue 4, Volume 7, October 202

5 Sensible Dehumidification emperature ( o C) Latent Dehumidification Absolute Humidity WSEAS RANSACIONS on HEA and MASS RANSFER this dicates that the results approached theritic and experiment, the results can be seen Figure 8. Sensible effectiveness of this system an average of 7.4% is shon Figure 9. Absolute humidity at the let air regeneration and dehumidification process ere kg H2O /kg dry.air and 05 kg H2O /kg dry.air respectively, ill result absolute humidity of air theoretic and experiment ere kg H2O /kg dry.air and kg H2O /kg dry.air respectively. From the results of these experiments is knon latent effectiveness this mode an average of 72.8%. his process can be seen Figure 0 and Fig.0 theoretical and experimental latent dehumidification Fig.8 theoretical and experimental sensible dehumidification Fig. dehumidification latent effectiveness 4.2 Regeneration Process Regeneration process aims to dry the silica gel desiccant heel order to function aga as a dehumidifier. Regeneration process the comg air is hot and dry air, and air that has been used for the regeneration temperature becomes loer and etter. Fig.9 dehumidification sensible effectiveness 4.2. Regeneration Process Mode () In the mode (2), theoretic and experimental regeneration process ith an average temperature ere 42 o C and 39.8 o C respectively, absolute humidity of air hich has been used for the regeneration process ill also crease, the theoretic and experimental an average ere 2 kg H2O /kg dry.air, and 8 kg H2O /kg dry.air respectively, it can be seen Figure 2 and 4. Average sensible and latent regeneration effectiveness ere 82% and 78.9% respectively, can be seen figure 3 and 5. While the adiabatic effectiveness desiccant heel can be seen Figure 24 is an average of 93%. E-ISSN: Issue 4, Volume 7, October 202

6 Absolute Humidity emperature ( o C) Sensible Regeneration emperature ( o C) Latent Regeneration WSEAS RANSACIONS on HEA and MASS RANSFER Fig.2 theoretical and experimental sensible regeneration Fig.5 regeneration latent effectiveness Regeneration Process Mode (2) heoretic and experimental regeneration process the mode (2) ith an average temperature ere 37.6 o C and 38 o C respectively, absolute humidity of air hich has been used for the regeneration process ill also crease, the theoretic and experimental an average ere kg H2O /kg dry.air, and 0.09 kg H2O /kg dry.air respectively, it can be seen Figure 6 and 8. Average sensible and latent regeneration effectiveness ere 72% and 72.8% respectively, can be seen figure 7 and 9. While the adiabatic effectiveness desiccant heel can be seen Figure 25 is an average of 96%. Fig.3 sensible regeneration effectiveness Fig.4 theoretical and experimental latent regeneration Fig.6 theoretical and experimental sensible regeneration E-ISSN: Issue 4, Volume 7, October 202

7 Latent Regeneration emperature ( o C) Absolute Humidity Absolut Humidity Sensible Regeneration emperature ( o C) WSEAS RANSACIONS on HEA and MASS RANSFER Air dehumidification process Air out dehumidification proces Air regenration process Fig.20 sensible desiccant heel process Fig.7 Sensible Regeneration effectiveness Fig.8 theoretical and experimental latent regeneration Absolute Humiditi of air regeneration process Ambolute Humidity of air Dehumidification process Absolute Humidity of air out dehumidification process Fig.2 latent desiccant heel process Dehumidification and Regeneration Process Mode (2) Fig.9 Regeneration latent effectiveness Air Dehumidification Process Air out Dehumidification Process Air Regeneration Process 4.3 Desiccant Wheel Process 4.3. Dehumidification and Regeneration Process Mode () Fig.22 sensible desiccant heel process E-ISSN: Issue 4, Volume 7, October 202

8 Adiabatic effectiveness (%) Adiabatic Absolute Humidity WSEAS RANSACIONS on HEA and MASS RANSFER 0.03 Absolute Humidity of air Regeneration Process Absolute Humidity of air dehumidification process 5 Absolute humidity of air out dehumidification process Fig.23 latent desiccant heel process 4.4 Adiabatic Effectifeness ) Fig.24 adiabatic effectiveness mode () the system is capable to evaporate of ater the dried material 0.8 kg H2O /h. If it is assumed that the material is dried eighg 00 kg hich has a moisture content of % itial and fal moisture content of 3% or the fal eight of 0.3 kg of material. hus this system should to evaporate ater the dried material as much as 89.7 kg H2O, then by usg equation (6) can be predicted dryg time 7.2 hours. 4. Conclusion In this study the desiccant heel is used for the dryer system. From the results obtaed that the desiccant heel suitable for the dryer system. Experiment results Mode () as better than mode (2) ith mean dryg air temperature and absolute humidity ere 58 o C and kg (H2O) /kg (dry air) respectively. Average Sensible and latent effectiveness ere 73% and 79.3% respectively. In the process of regeneration this system theoretic Sensible heat generatg temperature of 42 o C and experiment results of 39.8 o C, latten a theoretic process produces 2 kg H2O /kg dry.air, and the results of experiments 8 kg H2O /kg dry.air. Sensible effectiveness 0.82, hile the regeneration effectiveness latten 78.9%. With a flo rate of air to the dryg chamber,684.6 kg dry.air /hr, let air absolute humidity dryg chamber average of 0.067kg H2O /kg dry.air, at dryg efficiency of %, the system is expected to evaporate ater the dried material 0.8kg H2O /hr. Nomenclature Fig.25 Adiabatic effectiveness mode (2) 4.5 Dryg Estimate he results of experiments on this system dicates dry air flo rate,684.6 kg dry.air /hr, let air absolute humidity dryg chamber average of kg H2O /kg dry.air, at dryg efficiency of %, m m Effectiveness Mass air flo rate for dehumidification process (kg dry.air /hr) Mass air flo rate for regeneration process (kg dry.air /hr) m m Mimum value of either mass flo rate (kg dry.air /hr) Dry bulb temperature of air to dehumidification process ( o C) 2 Dry bulb temperature or air out from dehumidification process ( o C) 7 Dry bulb temperature of air to regeneration process ( o C) Dry bulb temperature of air out from 8 regeneration process ( o C) E-ISSN: Issue 4, Volume 7, October 202

9 WSEAS RANSACIONS on HEA and MASS RANSFER Absolute humidity of air to dehumidification process ( o C) Absolute humidity of air out from 2 7 dehumidification process ( o C) Absolute humidity of air to regeneration process ( o C) 8 Absolute humidity of air out from regeneration process ( o C) Absolute humidity of air enterg the dryg chamber (%) out Absolute humidity of air leavg the dryg chamber (%) Absolute humidity of the air enterg the as dryer at the pot of adiabatic saturation (%) h Enthalpy of air dehumidification process (kj/kg) h 2 Enthalpy of air out dehumidification process (kj/kg) s Dry matter content (%) t Dryg time (seconds) V Volumetric airflo rate (m 3 /s) W Weight of ater evaporated from the product (kg) WAC Water absorption capacity Density of air (kg/m 3 ) hc Heat collection efficiency p Pick-up efficiency s Dryg system efficiency G Dry air Mass air flo rate (kg dry.air /hr) a References: [] A. Fuoli, M. H. Ruslan, M. Y. Othman, M. Yahya, Supranto, A. Zaharim, and K. Sopian, 200. study of the double-pass solar air collector ith staggered fs, Proc. of the 9 th WSEAS Int. Conf. on SISEM SCIENCE and SIMULAION ENGINEERING (ICOSSSE 0), Japan, 200, pp [2] A. Fuoli, M. H. Ruslan, M. Y. Othman, M. Yahya, Supranto, A. Zaharim, and K. Sopian, 200. Collector efficiency of the double-pass solar air collector ith fs, Proc. of the 9 th WSEAS Int. Conf. on SISEM SCIENCE and SIMULAION ENGINEERING (ICOSSSE 0), Japan, 200, pp [3] A. Fuoli, K. Sopian, M. Y. Othman, M. H. Ruslan, M. A. Ghoul, A. Zaharim A and Zulkifly, Heat transfer correlation for the v- groove solar collector, Proc. of the 8 th WSEAS Int. Conf. on SIMULAION, MODELING and optimization (SMO 08), Spa, 2008, pp [4] A. Fuoli, K. Sopian, M. H. Ruslan, M. Y. Othman, and M. Yahya, Analytical and experimental studies on the thermal efficiency of the double-pass solar collector ith fned absorber American Journal of Applied Sciences, vol. 8, no. 7, pp , 20. [5] A. Fuoli, K. Sopian, M. H. Ruslan, M. Y. Othman, and M. Yahya,M. 20. hermal efficiency of double pass solar collector ith longitudal fs Absorbers, American Journal of Applied Sciences, vol. 8, no. 3, pp , 20. [6] A. Fuoli, K. Sopian, M. H. Ruslan, M.A. Alghoul, and M. Y. Sulaiman, Revie of solar dryers for agricultural and mare products, Reneable & Sustaable Energy Revie, vol. 4, pp. -30, 200. [7] A. Fuoli, M. Y. Othman, M. H. Ruslan, M. Yahya, A. Zaharim and K. Sopian, Design and testg of solar dryer for dryg ketics of seaeed Malaysia, Proc. WSEAS/NAUN Int. Conf. on Recent Research Geography, Geology, Energy, Environment and Biomedice, Greece, 20, pp [8] M. H. Ruslan, A. Fuoli, M. Y. Othman, M. S. M. Azmi, M. Yahya, A. Zaharim and K. Sopian, he double-pass solar dryer for dryg palm oil fronds, Proc. of the 0 th WSEAS Int. Conf. on System Science and Simulation Engeerg (ICOSSSE ), Malaysia, 20, pp [9] A. Fuoli, M. Y. Othman, M. H. Ruslan, M. Yahya, A. Zaharim and K. Sopian, he effects of dryg air temperature and humidity on dryg ketics of seaeed, Proc. WSEAS/NAUN Int. Conf. on Recent Research Geography, Geology, Energy, Environment and Biomedice, Greece, 20, pp [0] A.E. Kabeel. Dehumidification and humidification process of desiccant solution by air jection, Energy 35 (200) [] M. Ali Mandegari, H. Pahlavanzadeh. Introduction of a ne defition for effectiveness of desiccant heels, Energy 34 (2009) [2] Giovanni A. Longo, Andrea Gasparella. analysis on desiccant regeneration a packed column ith structured and random packg, Solar Energy 83 (2009) 5-52 [3] M.H. Ahmed, N.M. Kattab, M. Fouad. Evaluation and optimization ofsolar E-ISSN: Issue 4, Volume 7, October 202

10 WSEAS RANSACIONS on HEA and MASS RANSFER desiccant heel performance, Reneable Energy 30 (2005) [4] Stefano De Antonellis, Cesare Maria Joppolo, Luca Molaroli. Simulation, performance analysis and optimization of desiccant heels, Energy and Buildgs 42 (200) [5].S. Ge, Y.J. Dai, R.Z. Wang. Performance study of silica gel coated f-tube heat exchanger coolg system based on a developed mathematical model, Energy Conversion and Management 52 (20) [6] Mihajlo N. Golubovic, H.D.M. Hettiarachchi, William M. Worek. Sorption properties for different types of molecular sieve and their fluence on optimum dehumidification performance of desiccant heels, International Journal of Heat and Mass ransfer 49 (2006) [7] Giovanni Angrisani, Alfonso Capozzoli, Francesco Michiello, Carlo Roselli, Maurizio Sasso. Desiccant heel regenerated by thermal energy from a microcogenerator: assessment of the performances, Applied Energy 88 (20) [8] ri Suyono, K. Sopian, Sohif Mat, M. Yahya, M. H. Ruslan, and A. Zaharim. and Analysis of Desiccant heel performance for Lo Humidity Dryg system, Proc. Of 0 th WSEAS Int. Conf. on System Science and Simulation Engeerg (ICOSSSE ), Malaysia, 20, pp [9] Ayd Kilic. Lo temperature and high velocity (LHV) application dryg: Characteristics and effects on the fish quality, Journal of Food Engeerg 9 (2009) [20] Kosuke Nagaya, Yg Li, Zhehong J, Masahiro Fukumuro,Yoshori Ando a, Atsutoshi Akaishi. Lo-temperature desiccant-based food dryg system ith airflo and temperature control, Journal of Food Engeerg (2006) 7 77 [2] V. Shanmugama, E. Natarajan. vestigation of forced convection and desiccant tegrated solar dryer, Reneable Energy 3 (2006) E-ISSN: Issue 4, Volume 7, October 202