Available online at ScienceDirect. Procedia Engineering 90 (2014 )

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1 Aville online t ScienceDirect Procedi Engineering 90 (2014 ) Astrct 10th Interntionl Conference on Mechnicl Engineering, ICME 2013 Prmetric nd performnce nlysis of nturlly ventilted floriculture greenhouse using therml model Aritr Gnguly*, Bipl Buri Deprtment of Mechnicl Engineering, Bengl Engineering & Science University, Shipur, Howrh , West Bengl, Indi Greenhouse technology is method of cultivtion of flowers, vegetles nd medicinl plnts under controlled environment. The min ojective of the greenhouses locted in the plins of Indi is to protect the plnts from excessive sensile het from the solr rdition nd mient temperture. The structure lso protects the plnts from the storm nd pest. Nturl ventiltion (long with shding screens) cn e employed to regulte the required greenhouse microclimtn cost effective mnner. In the present pper the uthors nlyze the performnce of greenhouse from the view point of cultivtion of vrieties of Gerer flower using therml model developed nd presented erlier. Prmetric nlysis hs een done to understnd the effect of vrious crop, design nd climtic prmeters on the performnce of the system. From the performnce nlysis of the greenhouse, it is reveled tht the plnt lef temperture could e mintined within the permissile limit for the cultivtion of the trget flowers for vrious sesons of climtic cycle. The study revels tht the nturl ventiltion long with shding in greenhouse cn led to the sustinle cultivtion of trget flowers in the region under considertion The The Authors. Pulished y Elsevier y Elsevier Ltd. This Ltd. is n open ccess rticle under the CC BY-NC-ND license ( Selection nd peer-review under responsiility of the Deprtment of Mechnicl Engineering, Bngldesh University of Selection Engineering nd peer-review nd Technology under responsiility (BUET). of the Deprtment of Mechnicl Engineering, Bngldesh University of Engineering nd Technology (BUET) Keywords: Greenhouse; Nturl Ventiltion; Therml Model; Trnspirtion; Lef Are Index; Chrcteristic Length of Lef; Shding Effect. 1. Introduction Greenhouses re structures covered with suitle trnsprent mteril inside which the climtic conditions re rtificilly nurtured to optimize the growth of plnts. The structure lso protects the plnts from the dverse climtic conditions such s storm, cold, precipittion, excessive solr rdition, etc. The technology of greenhouse emnted erlier in the western countries of the world primrily to protect the plnts from extreme cold nd frost. So the min ojective of the greenhouses locted in the western countries is heting nd humidifiction. But in the plins of * Corresponding uthor. Tel.: ; fx: E-mil ddress: ritr@mech.ecs.c.in The Authors. Pulished y Elsevier Ltd. This is n open ccess rticle under the CC BY-NC-ND license ( Selection nd peer-review under responsiility of the Deprtment of Mechnicl Engineering, Bngldesh University of Engineering nd Technology (BUET) doi: /j.proeng

2 486 Aritr Gnguly nd Bipl Buri / Procedi Engineering 90 ( 2014 ) Indin sucontinent, the climte remins hot for greter prt of yer, while the costl res experience hot nd humid climte. The high temperturs detrimentl to the growth of plnts, while high mient humidity promotes the growth of pests tht destroy considerle vegettion in open field. So for greenhouses locted in the plins of Indi (in Gngetic Bengl), the min ojectives re control of high temperture, intensity of solr rdition nd protection from the storm nd pests. Mny rtificil methods like fn-pd evportive cooling, fogging, misting etc, hve een pplied to cool the greenhouse microclimte, ut the min constrints for ll those methods re the involvement of high cost nd the requirement of electricity. In Indi, there re out un-electrified villges, of which villges re locted in such remote res tht the extension of electricity grid thers not economiclly vile [1]. So nturl ventiltion long with shding screens continue to e the most promising nd cost economic method for regultion of the microclimtn greenhouse. The purpose of the present work is to nlyze the performnce of floriculture greenhouse under nturl ventiltion from the view point of cultivtion of certin trget flowers like vrieties of Gerer for vrious sesons of climtic cycle. The nlysis hs een done using therml model developed y the uthors erlier [2]. In the present work prmetric nlysis hs lso een included (using the model) to understnd the effect of vrious crop, geometric nd climtic prmeters on the performnce of the system. Gerer flower cn e est grown t dy tempertures etween C though the flowering gets ffected minimlly till temperture of 31 0 C [3]. After tht the productivity strts reducing nd eyond 35 0 C, the flowering gets dversely hrmed [3]. On the lower side, though the optimum temperturs 23 0 C, yet the cultivtion is fesile t still lower tempertures. As the climtic condition of Gngetic Bengl remins hot for greter prt of yer nd the mient dy temperture seldom decreses elow 18 0 C in winter, so we re more concerned out the upper limit of the temperture rnge. So in the present nlysis we hve considered tht the trget dylong greenhouse temperture should e within 31 0 C. 2. Therml Model Development The uthors hve erlier presented detiled therml model of nturlly ventilted floriculture greenhouse [2]. The min governing equtions of the therml model re presented in rief in this section: In Eq. (1), K C denotes the overll het trnsfer coefficient of greenhouse roof covering, K S the sensile het trnsfer coefficient of ventiltion nd K L represents the ltent het trnsfer coefficient of ventiltion which is dependent on mny fctors s descried in detil in the erlier pper [2]. Plnt trnspirtion rte (λe) which significntly influences the microclimte of greenhouse minly depends on stomtl resistnce (r st ) nd

3 Aritr Gnguly nd Bipl Buri / Procedi Engineering 90 ( 2014 ) erodynmic resistnce (r ) of lef (s given y Eq. (4)) [4]. The lef resistnces to trnspirtion (r st nd r ) depends on the trnsmissivity of the greenhouse covering (μ), mient solr rdition intensity ( ), chrcteristic length of lef (d f ) nd greenhousnside wind speed (U i ) s given y Eqns. (5) nd (6) [5]. Knowing the greenhouse prmeters (K C, K S, K L nd μ), the crop prmeters (I LA, d f, r nd r st ) nd the mesured mient climtic conditions (, nd e o ), the three unknown vriles ( T, o nd Δe) in eqns. (1), (2) nd (3) hve een deduced nlyticlly using Guss-Siedel itertion technique. 3. Results nd Discussion A computer codn C lnguge hs een developed to predict the hourly greenhousr temperture, plnt lef temperture nd thnside humidity considering monthly verge vlues of hourly dt for solr rdition intensity, mient temperture, reltive humidity nd the wind speed for Kolkt long with the crop dt s input. [6, 7] 3.1. Prmetric Anlysis of the Therml Model Figure 1() shows the vrition of verge greenhousr temperture ( ), plnt lef temperture ( ) nd thr wter vpour pressure ( ) with lef rndex (lef re per plnt to the lnd re per plnt) for given vlue of solr rdition intensity, mient temperture, humidity, wind speed nd chrcteristic length of lef (d f ). The climtic dt used here pertins to the dt corresponding to 12 Noon for the month of Decemer A shding of 50% hs een pplied to restrict the entry of solr rdition inside the greenhouse. As oserved from the figure, oth the greenhousr nd plnt lef temperture decrese with incresn the vlue of lef rndex. As the lef rndex is incresed from 2.5 to 5.0, thers out 1.8 C drop in the greenhousr temperture, while the plnt lef temperture decreses y out 1.5 C. The reson for this is tht with thncresn lef rndex, the wter loss from the plnt y trnspirtion increses through the lef stomt openings(s shown in Fig. 1()) resulting in lowering of the temperture nd thncresn greenhousr wter vpour pressure % Shding Lef Are Index Greenhouse Air Vpour Pressure (P) Trnspirtion Loss (W/m 2 ) % Shding Lef Are Index Fig. 1. () Vrition of greenhousr temperture, lef temperture nd ir wter vpour pressure with vrition of lef rndex; () Vrition of trnspirtion loss with vrition of lef rndex. Figure 2() shows the vrition of greenhousr temperture ( ), plnt lef temperture ( ), nd thr wter vpour pressure ( ) for vrious chrcteristic length of lef (d f ), for the month of Decemer (2009) considering the lef rndex to e constnt nd other prmeters sme s used in Fig. 1(). As evident from the figure, oth the greenhousr nd the plnt lef temperturncrese with thncresn the chrcteristic length of lef, while the

4 488 Aritr Gnguly nd Bipl Buri / Procedi Engineering 90 ( 2014 ) greenhousr wter vpour pressure decreses. This is due to the fct tht thers incresn erodynmic resistnce (r ) of lef (s given y Eq. (5)) tht leds to lower wter loss through trnspirtion s shown in Fig. 2 () % Shding Chrcteristic Length of Lef (m) Greenhouse Air Vpour Pressure (P) Trnspirtion Loss (W/m 2 ) Trnspirtion Loss r r s 50% Shding Chrcteristic Length of Lef (m) Lef Resistnce (s/m) Fig. 2.() Vrition of greenhousr, plnt lef temperture nd ir wter vpour pressure with chrcteristic length of lef; () Vrition of trnspirtion loss, erodynmic resistnce nd stomtl resistnce of lef with vrition of chrcteristic length of lef. Figure 3() shows the vrition of greenhousr temperture ( ), plnt lef temperture ( ) nd greenhousr wter vpour pressure ( ) with re of ventiltion keeping other prmeters constnt. It is found tht with the incresn the re of openings oth greenhousr nd plnt temperture decreses. Similr trend is oserved with insidr wter vpour pressure. This is due to the fct tht with incresn the vent opening re the volume flow rte of ir increses leding to more het trnsfer from the greenhouse to mient d f =0.025 m % Shding Greenhouse Air Vpour Pressure (P) = C =600 W/m 2 =80% 75% Shding Greenhouse Air Vpour Pressure (P) Ventiltion Are (m 2 ) Amient Wind Speed (m/s) Fig. 3. () Vrition of greenhousr, lef temperture nd ir wter vpour pressure with ventiltion re; () Vrition of greenhousr, lef temperture nd ir wter vpour pressure with mient wind speed. Figure 3() shows the vrition of greenhousr temperture ( ), plnt lef temperture ( ), nd ir wter vpour pressure ( ) s predicted y the model for different mient wind speeds keeping other prmeters constnt. It is found from the figure tht with thncresn the wind speed, the temperture decreses. This is due to the fct tht with incresn the wind speed, the ventiltion rtncreses nd the erodynmic resistnce of the plnt lef

5 Aritr Gnguly nd Bipl Buri / Procedi Engineering 90 ( 2014 ) reduces (s given y Eq.(5)), incresing the rte of plnt trnspirtion (Eq. (4)). Thus, due to the comined effect of oth incresn the trnspirtion rte nd the rte of ventiltion, thers shrp decresn the greenhousr nd plnt lef temperture. Also, thnsidr wter vpour pressurs found to decrese with wind velocity Performnce Anlysis of the Greenhouse for Different Sesons of Climtic Cycle In the present section, the therml model hs een used to nlyse the performnce of the greenhouse for cultivtion of the Gerer flower for vrious sesons of full climtic cycle. Figure 4() shows the hourly vrition of mient temperture ( ), greenhousr temperture ( ) nd plnt lef temperture ( ) for the month of Jnury 2009 for given vlue of lef rndex (3.5) nd chrcteristic length of lef (0.025m). As reveled from the figure, the greenhousr nd plnt lef temperturncreses with the time of the dy reching mximum vlue round 12 Noon nd then gin decreses. The lef temperturs found to increse gin instntneously t 5 PM (during sunset) due to momentry decresn the rte of plnt trnspirtion t tht instnt of time owing to incresn erodynmic resistnce (due to reduction in wind speed) nd mximum vlue of stomtl resistnce (due to minimum intensity of solr rdition). It is oserved from the figure tht the greenhouse plnt temperture cn e restricted within 26 0 C ll through the dy which is highly conducive for the growth of the trget flowers considered in the study. The greenhousr temperture cn lso e mintined within 28 0 C throughout the dy % Shding LAI= % Shding 27 T 26 d i f =0.025m Time of The Dy (Hours) 22 Time of The Dy (Hours) Fig.4. () Vrition of greenhousr temperture, plnt lef temperture nd mient temperture with time for the month of Jnury 2009; () Vrition of greenhousr temperture, plnt lef temperture nd mient temperture with time for the month of Mrch Figure 4() shows the hourly vrition of mient temperture ( ), greenhousr temperture ( ) nd plnt lef temperture ( ) for the month of Mrch 2009 keeping lef rndex nd chrcteristic length of lef s constnt. As seen from the figure, the greenhousr nd the plnt lef temperturncreses with the time of the dy reching mximum t round 1PM nd then reduces. The lef temperturs found to increse gin instntneously t 6 PM (during sunset) s discussed erlier (for Fig. 4()). It is oserved from Fig. 4() tht the plnt lef temperture cn e restricted within 28 0 C ll through the dy which is highly conducive for the growth of the vrieties of Gerer flower. Thr temperture cn lso e mintined within 31 0 C lmost throughout the dy except during the pek rdition hours (12 Noon to 3PM) when it mrginlly exceeds eyond 31 0 C. Figure 5() shows the hourly vrition of mient temperture ( ), greenhousr temperture ( ) nd the plnt lef temperture ( ) for the month of July for given vlue of lef rndex nd chrcteristic length of lef. It is

6 490 Aritr Gnguly nd Bipl Buri / Procedi Engineering 90 ( 2014 ) oserved tht the plnt temperture cn e restricted within 30 0 C ll through the dy. Thr temperture cn lso e mintined within 31 0 C lmost throughout the dy except during 11AM to 1PM when thr temperture mrginlly exceeds eyond 31 0 C. Figure 5() shows the hourly vrition of mient temperture ( ), greenhouse ir temperture ( ) nd plnt lef temperture ( ) for the month of Septemer keeping other prmeters sme s mentioned in the Fig. 5.(). It is oserved from Fig. 5() tht the plnt temperture cn e restricted within 30 0 C ll through the dy which is within the trget rnge. Thr temperture cn lso e mintined within the trget vlue of 31 0 C lmost throughout the dy except during the pek rdition hours when it mrginlly exceeds 31 0 C % Shding LAI= % shding Time of The Dy (Hours) 26 Time of The Dy (Hours) Fig.5. () Vrition of greenhousr temperture, plnt lef temperture nd mient temperture with time of the dy for the month of July 2009; () Vrition of greenhousr temperture, plnt lef temperture nd mient temperture with time of the dy for the month of Sept Conclusion The present work discuses the prmetric nd performnce nlysis of nturlly ventilted floriculture greenhouse for the climtic conditions of Gngetic Bengl in Indin sucontinent using therml model. It is reveled from the study tht the microclimtn the greenhouss significntly influenced y the crop prmeters such s lef rndex, chrcteristic length of lef nd the rte of plnt trnspirtion. The mient wind speed nd the greenhouse design in terms of vent re lso ply significnt role. From the yer round performnce nlysis, it is reveled tht the greenhouse plnt temperture nd thnsidr temperture cn e mintined within the trget rnge for the cultivtion of the vrieties of Gerer except few instnces in the month of Mrch, July nd Septemer when the temperture vlues mrginlly exceed the trget. The study thus revels tht the nturl ventiltion long with shding in greenhouse cn led to sustinle cultivtion of the trget flowers in the region. References [1] R.M. Mohril, P.S. Kulkrni, A Cse Study of Solr Photovoltic Power System t Sgrdeep Islnd, Indi, Renew. Sust. Energ. Rev. 13 (2009) [2] B. Buri, A. Gnguly, Effect of crop trnspirtion on the microclimte of nturlly ventilted greenhouse, Int. J. of Emerging Technology nd Advnced Eng. 3 (2013) [3] A. Kumr, Gerer Mnul, KF Bioplnts Pvt Ltd., 2012, pp. 1-18, ville online t ccessed on Apr 28, 2013 t 11:05PM IST. [4] K.S. Kumr, M.K. Jh, K.N. Tiwri, A. Singh, Modeling nd evlution of greenhouse for floriculturn sutropics, Energ Buildings. 42 (2010) [5] H. Ftnssi, T. Boulrd, J. Lgier, Simple Indirect Estimtion of Ventiltion nd Crop Trnspirtion Rtes in Greenhouse, Biosystems Eng. 88 (2004) [6] T.A. Roerto, V.F. Mrcos, P. C. René, Convection regime etween cnopy nd ir in greenhouse, Sci. Agric. 63 (2006) [7] Wether Dt otined from Regionl Meteorologicl Centre (RMC), Kolkt, 2009.