Energy Conversion and Management 51 (2010) 360–364Contents lists available at ScienceDirect Energy Conversion and Management journal homepage: www.elsevier.com/locate/enconman Fuel and energy saving in open pan furnace used in jaggery making through modified juice boiling/concentrating pans S.I. Anwar * Division of Agricultural Engineering, Indian Institute of Sugarcane Research, Raebareli Road, Lucknow 226 002, UP, India a r t i c l e i n f o Article history: Received 6 May 2008 Received in revised form 21 February 2009 Accepted 30 September 2009 Available online 25 October 2009 Keywords: Energy saving Jaggery making furnace Sugarcane bagasse Heat transfer Fins a b s t r a c t In this paper the concept of fins has been used for heating purpose for improving efficiency of open pan jaggery making furnace. Pan is the integral part of these furnaces where boiling/concentration of sugarcane juice take place. Parallel fins were provided to the bottom of main pan and gutter pan of IISR Lucknow 2-pan furnace. Choice for type of fins was based on movement of flames and hot flue gases generated due to combustion of bagasse. Fins helped in more heat transfer to the sugarcane juice being concentrated. Considerable improvement in heat utilization efficiency (9.44%) was observed which resulted in saving of fuel and energy (31.34%). Ó 2009 Elsevier Ltd. All rights reserved. 1. Introduction Sugarcane is grown in an area of about 4 million hectares of land in India with an average yield of 66 tonnes per hectare. With this about 273 million tonnes of sugarcane is produced annually. This sugarcane is processed for making sweeteners like sugar, jaggery or khandsari. Out of total sugarcane produced, 66.7% is used for making sugar and 20.7% is utilized by jaggery and khandsari under the decentralized sector. Remaining is used for seed, feed, chewing or raw juice drinking purposes [1]. Sugarcane juice concentration, while processing sugarcane for above sweeteners, is one of the important unit operations. This is done quite efficiently in multi-effect evaporators in well-equipped sugar mills. Evaporation of water takes place under vacuum at lower temperature. This helps in reduction of sugar loss due to burning and also helps in reduction in colour development. Jaggery and khandsari, on other hand, are manufactured in decentralized units, which are located mostly in rural areas. Due to technological limitations of these units, they employ open pan furnaces for juice concentration. Sugarcane bagasse is the primary fuel used in jaggery making furnaces, which is obtained during the process of juice extraction/ cane crushing. It mainly contains fibres, sugars and water and its net calorific value is the result of calorific value of its constituents (fibre – 19259 kJ/kg, sugar – 16747 kJ/kg and water – nil) [2]. Manohar rao [3] reported that wet mill bagasse has moisture 50%, fibre 47%, sugar 2.5% and mineral 0.5%. Before using it as fuel, * Fax: +91 522 2480738. E-mail address:
[email protected]. 0196-8904/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.enconman.2009.09.033 bagasse is dried in counter-current type tunnel driers in most of the sugar mills but is normally sun dried in jaggery units. Many types of jaggery making furnaces have been developed in India [4]. Main variation in designs was due to number and size of pans, size of combustion chamber, size and geometry of flue gas channel, height of chimney, provision for air supply, etc. Hemispherical bottom pans are generally in use with these furnaces. Shortage or even no saving of fuel is very common with these furnaces due to low heat utilization efficiency. The fibres of sugarcane rind are excellent source of raw material for paper and pulp industries; the pith portion may effectively be converted and utilized as animal feed. So saving of bagasse may lead to the way for extra revenue generation for jaggery manufacturer. Lower efficiency also results in increased processing time of sugarcane juice so the product quality and productivity are also affected. Indian Institute of Sugarcane Research, Lucknow (India) has also developed a 2-pan furnace. Juice is boiled/concentrated in circular flat-bottom main pan and a rectangular gutter pan has been provided over the flue gas passage for preheating of juice to be concentrated in the subsequent lot. The furnace with all of its components is shown in Fig. 1 [5]. There has been limited effort made to improve the energy receiving component of the system, especially to improve the energy transfer efficiency from the flame to the pan. In normal cooking, when a pan is placed over fire heat transfer takes place through convection and radiation. Combustion products and air form an insulating layer below the pan bottom resulting into poor heat transfer. Fins are useful in breaking the insulating layer and provide additional metallic area for heat transfer. In jaggery This feature has been applied in IISR furnace. An analysis was carried out to study the efficiency of straight fins of different configurations when subjected to simultaneous heat and mass transfer mechanism by Sharqawy and Zubair [13]. From the results. These were welded lengthwise in the direction of movement Fig.S. and others can be improved to achieve favorable heat transfer characteristics in addition to its main functions such as rigid fixation properties. For simplicity in fabrication. Khaled [11] modeled and analyzed analytically the heat transfer through joint fins. Naphon [8] studied the heat transfer characteristics of the annular fin under dry-surface. Analytical solutions are obtained for temperature distribution over the fin surface when the fin is fully wet. and fully wet-surface conditions. highly accurate results are obtained. The effect of atmospheric pressure on the fin efficiency was also studied. usage of fins is not new but such concept for heating purpose in jaggery making open pan furnaces has not been tried yet. Malekzadeh and Rahideh [7] also did an incremental differential analysis (IDQ) of the two-dimensional non-linear transient heat transfer analysis of variable section annular fins. Rosario and Rahman [10] presented the analysis of heat transfer in a partially wet annular fin assembly during the process of dehumidification. kJ/kg such as bolts. partially wet and fully dry surface conditions were carried out by Kundu [9]. Huang and Shah [14] presented a critical assessment of different idealizations and some specific design recommendations were made for the determination of the fin efficiency for plate-fin heat exchangers. [6] have done shape optimization of nonsymmetric. convective–radiative annular fins. % mass of water evaporated. Anwar / Energy Conversion and Management 51 (2010) 360–364 361 Nomenclature gHu Mev L heat utilization efficiency. Calculations were carried out to study the performance of the heat exchanger. mild steel flats of 40 5 mm size were welded at 60 mm spacing to the bottom of main juice boiling pan and gutter pan. 1. Thermal analysis and optimization of longitudinal and pin fins of uniform thickness subject to fully wet. The mathematical models were developed and solved by the central finite difference method to obtain temperature distribution along the fin. Malekzadeh et al. Although. . IISR Lucknow furnace used for jaggery making. in addition to fin optimum dimensions. 2. Experimental set-up and procedure Main pan and gutter pan of IISR furnace were modified in which fins were provided to the bottom of these pans. kg calorific value of bagasse. The computed results included the temperature distribution in the wall and the fin and the fin efficiency. flames and hot flue gases drift towards exit and therefore get a longer path and duration for effective heat transfer.I. it was also highlighted that for the same thermo-geometric and psychometric parameters. The work showed that the design of machine components mb Cb mass of bagasse consumed. kJ/kg making furnaces. kg latent heat of evaporation of water. a longitudinal fin gives higher efficiency than the corresponding pin fin irrespective of surface conditions. partially wet-surface. Lin and Jang [12] did a twodimensional analysis of combined heat and mass transfer in elliptic fins and found that both the fully dry and wet elliptic fin efficiencies are up to 4–8% greater than the corresponding circular fin efficiencies having the same perimeter. Less computational efforts of the method with respect to the finite difference method is shown. It was shown that by using fewer grid points. screws. 2. Total quantity of water evaporated was calculated by subtracting water left in both the pans from the total water filled. 7–120.0.0. Table 1 Effect of fins on area of heat receiving surfaces.) Fig.6. capacity 1 l.6. Anwar / Energy Conversion and Management 51 (2010) 360–364 of flue gases and thus have been named as parallel fins. Based on total quantity of water evaporated and the quantity and calorific value of used bagasse.83 kg/min). The experimental error has been evaluated in terms of per cent uncertainty (internal + external) [15]. with conventional and with modified systems have been shown in Fig.1 kg) and was burnt in the furnace for 120 min maintaining a uniform feed rate (0.1. 14–113. 17–84.5.0.0.I.83 kg/min). the possibility of errors in taking measurements of bagasse weight. 3. Experiments were replicated thrice for each system and average values were calculated.362 S. 11–126.2 cm) were welded to main pan and 10 flats of 122 cm each were welded the bottom of gutter pan. 3.0. The performance of furnace was evaluated with conventional and modified pans by water boiling test as mentioned below: One hundred and fifty litres of water was filled in main pan and in gutter pan. 1000 kg capacity. Following two equations have been used for internal uncertainty: U1 ¼ qffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi r21 þ r22 þ þ r2N ð2Þ N where r is the standard deviation and is given as ð3Þ and X X is the deviation of observation from the mean and N and N0 are the number of sets and number of observations in each set. 1–30. Temperature profile of water in conventional and modified main pan and gutter pan. 2.0.7. 16–95. 9–126. (1). 18–65. respectively. heat utilization efficiency was calculated using Eq.5. 3–85.e. 4–97. 8–124. 10–126.69 cm2 27561. 3. Water temperature in main and gutter pan was noted down by using mercury-in-glass thermometer (ZEAL make: range 0–110 °C. Water left in both the pans was measured with measuring cylinder (glass type. ð1Þ 2. The increase in area of heat receiving surface due to fins was calculated as: Increase in area ¼ 2 total length of flat provided width of flat Effect of fins on area of heat receiving surfaces is given in Table 1 and modified main pan and gutter pan are shown in Fig.2. The per cent internal uncertainty has been determined using the following expression: % internal uncertainty ¼ U1 Average of total number of observations 100 ð4Þ External uncertainty has been calculated by considering least count of instruments used in recording data. 2–63.0. Experimental results and discussion Temperature profile of water in main pan and in gutter pan for both the systems i.8. least count 0. Chain welding was done in two passes to avoid bending of flats and also to have continuous welding throughout the length of flats providing better contact.29 cm2 118% Conventional Modified Increase in area 7442 cm2 17202 cm2 131% Main Pan (conventional) Gutter Pan (conventional) Main Pan (modified) Gutter Pan (modified) 100 90 80 Temperature (°C) Conventional Modified Increase in area M ev L 100 mb C b sffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi P ðX XÞ2 r¼ N0 2. Nineteen flats (size. Therefore. Gutter pan 12667. water quantity and temperature has been considered. 19–31. 15–106. Fig.0.8.5. water was allowed to remain in the pans for next 2 h. This was done to facilitate utilization of maximum amount heat and the water to cool down for ease in its measurement. 12–124.0. 5–107. 13–120. . Test with modified pans Similar method was followed with modified pan except the quantity of bagasse taken was 75 kg and the feeding was done for 90 min (feed rate 0.5. Hundred kilogram of bagasse was weighed using electronic balance (Decibel make: platform type. least count 0. After consuming the weighed quantity of bagasse in the specified time. Test with conventional pans Main pan gHu ¼ 70 60 50 40 30 20 10 0 0 20 40 60 80 100 120 Time (min. least count 1 °C) at 5min interval. Modified main pan and gutter pan. 6–114.01 l). 19 0.12 I II III Average 150 150 300 90 75 164. kg Sl no. l Total water taken. The effect of fins is more pronounced in gutter pan where water temperature reached to 81 °C in just 90 min with modified pan as compared to 76 °C that too in 120 min with conventional pan. respectively. % I II III Average 150 150 300 120 100 148.48 0. min Bagasse used.67 20.24 2. Particulars Experiment number 1 2 3 4 5 6 7 8 9 Weight of water in main pan.10 150 150 300 120 100 149. Therefore about 48% more water is evaporated in case of modified pans.18 0.46 29. 6. Water evaporation per unit weight of bagasse is shown in Fig.21 kg for modified pans.483 0. 4. kg Water evaporated/kg of bagasse. Particulars Experiment number 1 2 3 4 5 6 7 8 9 Weight of water in main pan.4 0. kg Water evaporated/kg of bagasse.68 20. It may be seen from above tables that about 15 kg more water was evaporated by using modified pans that too with 75 kg bagasse. Effect of modified pans on water evaporation.49 0.48 HUE.12 20 15 10 0.I. kg 0. Experimental results with conventional and modified pans have been summarized in Tables 2 and 3.71 kg) with modified pans. % It can be seen that there is advancement in time of boiling in the main pan in the modified system and the water started boiling 6 min earlier than the conventional pan.46 29.31 2. min Bagasse used. kg Total water evaporated. kg Total water evaporated.63 150 150 300 90 75 164.5 5 0 0 Conventional Modified Pan Fig. Conventional Modified Pan Fig. kg Heat utilization efficiency.8 1 20.5 2. kg Bagasse used/kg of water evaporated. Effect of modified pans on bagasse consumption.82 2. 35 2.46 kg per kilogram of water evaporated in case of modified system against 0. It is more (0.67 in case of conventional system resulting in reduction by 0.3 0.1 0 Conventional Modified Pan Fig.46 29.49 150 150 300 90 75 164.08 150 150 300 120 100 149. l Time of operation. 5. l Time of operation. 4. .46 0.56 30 2 25 1.2 0.59 2.67 20. 0. energy and fuel saving of 31.76 1. Sl no.5 1. kg Total water taken. The effect of modified pans on bagasse consumption has been shown in Fig. l Weight of water in gutter pan.67 0.19 0.19 29.35 1. kg Bagasse used/kg of water evaporated.48 0.46 29.68 20.5 0.363 S. Effect of modified pans on heat utilization efficiency.16 150 150 300 120 100 148.01 1.34% was achieved by using modified Bagasse consumed per kilogram of water evaporated.6 0. % Water evaporated per kilogram of bagasse.56 Table 3 Results of water boiling test with modified pans.58 150 150 300 90 75 163.19 0. Therefore. It is 0. kg Weight of water in gutter pan.92 1. kg Heat utilization efficiency.7 0. Anwar / Energy Conversion and Management 51 (2010) 360–364 Table 2 Results of water boiling test with conventional pans. 5. New Delhi: ISPCK Publishers and Distributors. [12] Lin Chien-Nan. Setoodeh AR. [5] Baboo B. 6.48(5):1671–7.33(1):112–21.128(2):203–6. Optimization of non-symmetric convective–radiative annular fins by differential quadrature method. 4. Int J Heat Mass Transfer 2002. Study on the heat transfer characteristics of the annular fin under dry-surface. IDQ two-dimensional nonlinear transient heat transfer analysis of variable section annular fins.45(18):3839–47. New Delhi: ICSC. Conclusions The heat utilization efficiency of jaggery making furnace increased considerably by using modified pans having fins. Appl Therm Eng 2007. 1982. No. Co-operative Sugar. [6] Malekzadeh P. References [1] Anon.13(3):282–93.27(5–6):976–87. Analysis of heat transfer in a partially wet radial fin assembly during dehumidification. Int J Heat Fluid Fl 1999. 2007:38(6).364 S. By products of cane sugar industry. Int Commun Heat Mass Transfer 2006.20(6):642–8. Lucknow: Indian Institute of Sugarcane Research.56% from 20. [13] Sharqawy MH. [15] Nakra BC. Jang Jiin-Yuh. Anwar / Energy Conversion and Management 51 (2010) 360–364 pans. Improvement in efficiency would also be helpful for quality enhancement of the product due to less time requirement for sugarcane juice concentration in jaggery making. A two-dimensional fin efficiency analysis of combined heat and mass transfer in elliptic fins. The saved bagasse can be diverted to subsidiary industry like paper and pulp for extra revenue generation and the whole economics of the system would improve. 1977. It increased to 29. Anwar SI. partially wet-surface. India: National Federation of Co-operative Sugar Factories Ltd.I. Assessment of calculation methods for efficiency of straight fins of rectangular profile. [11] Khaled ARA. [2] Paturao JM. an increase of 9. New Delhi. Instrument measurement and analysis. Performance and optimum design analysis of longitudinal and pin fins with simultaneous heat and mass transfer: unified and comparative investigations.12% in case of conventional pans. Monograph on the Gur industry of India. Effect of modified pans on heat utilization efficiency is shown in Fig. In other terms per cent increase in heat utilization efficiency was 46. and fully wet-surface conditions. Energy Convers Manage 2007. Chaudhary KK. [4] Roy SC. Recent developments in jaggery (Gur) research. [10] Rosario L. [9] Kundu B. Modification resulted in saving of fuel and energy. Rahman MM. [8] Naphon P.48(1):269–76. Amsterdam-Oxford-New York: Elsevier Scientific Publication Company. J Heat Transfer 2006. Energy Convers Manage 2007. Int J Heat Fluid Fl 1992. [3] Manohar rao PJ.. Shah RK. Tech Bull. Zubair SM.28(17–18):2279–88. India: Tata McGraw Hill Publication Company. 1951. [14] Huang LJ. Maximizing heat transfer through joint fin systems. Rahideh H.92. [7] Malekzadeh P. IISR/JKS/94/91995. Therefore. Industrial utilization of sugar and its by products. 1991. Rahideh H.44% was achieved. Due to saving of bagasse there would be reduction of undesirable generation of CO2 also. The values of the per cent uncertainty ranged between 19% and 27% for all the cases. 1995. Appl Therm Eng 2008. . Efficiency and optimization of straight fins with combined heat and mass transfer – an analytical solution. The saved bagasse can be diverted to paper and pulp industry for extra revenue generation.