Mohammad ALI BEHAEEN, Asgar MAHMOUDI, Seyed FARAMARZ RANJBAR

Nar’ın Farklı Katmanlarında Geçici Isı Transferindeki Soğutma Parametreleri Üzerinde Zorlanmış Hava ile Soğutma Performansının Değerlendirilmesi

Bahçe tarımında yetiştirilen ürünlerin kalitesi, ileri teknikler kullanılarak muhafaza edilebilir. Bu yöntemlerden birisi de depolamadan önce uygulanan ön soğutma ile meyvenin raf ve depolama ömrünün uzatılmasıdır. Bu nedenle, nar (Punica granatum L.)’ın merkezinde (tanede), süngerimsi dokusunda (iç zarda) ve derisinde (kabukda) zorlanmış hava ile soğutmada, soğutma hızının etkilerini araştırmak amacıyla bu çalışma ortaya konulmuştur. Ürünlerin soğutulmasında etkili faktör olarak 0.5, 1 ve 1.3 m s-1 değerlerindeki üç farklı hava hızı ve 7.2 °C sıcaklık değeri dikkate alınmıştır. Deneysel verilerden, ısı transferi direnç faktörü ve soğutma katsayısını içeren soğutma parametreleri hesaplanmıştır. Ayrıca, narın farklı katmanlarındaki yarı soğuma süresi ve sekizde yedi soğuma süreleri elde edilmiştir. Soğutma heterojenliği, farklı hava hızlarında ve narın farklı katmanlarında analiz edilmiştir. Sonuçlar, hava hızının 0.5 m s-1’den 1.3 m s-1 arttığında, yarı soğuma süresinin ve sekizde yedi soğutma süresinin azaldığını göstermiştir. 5000. saniyeden sonra hava hızındaki değişimin, narın farklı katmanlarındaki sıcaklığın azalması üzerinde etkisi oldukça hafif olmuştur. Soğutma heterojenliği, 0.5 m s-1 hava hızında düşük olup sonraki 1 m s-1 hava hızında artmıştır. Sonuç olarak, 1.3 m s-1 hava hızı uygun bulunmamıştır. Genel sonuçlar, soğutma sürecindeki kararsız ısı iletimini açıklayan bu araştırmada uygulanan metodolojinin, nar veya benzer şekildeki meyvelerde de uygulanabileceğini göstermektedir.

An Evaluation of the Performance of Forced Air Cooling on Cooling Parameters in Transient Heat Transfer at Different Layers of Pomegranate

The quality of horticultural products can be promoted using high techniques. One of these methods is precooling applied before storage and leads to increased shelf and storage life of the fruit. For this reason, the effect of forced air cooling was conducted to investigate the cooling rate at the center (aril), spongy tissue (peel) and leathery skin (rind) of pomegranate (Punica granatum L.). Airflow velocity as an effective factor in cooling products at three levels of 0.5, 1, and 1.3 m s-1 and temperature of 7.2 °C was considered. Cooling parameters including lag factor and cooling coefficient were calculated from experimental data. Then, half-cooling time and seven-eighths cooling time were obtained at different layers of pomegranate. Cooling heterogeneity was analyzed at different air velocity and at different layers of pomegranate. The results showed that increase in air velocity from 0.5 to 1.3 m s-1, reduced the half-cooling time and seven-eighths cooling time. After 5000 seconds, the change of air velocity had a slight influence on decreasing temperature of different layers of pomegranate. Cooling heterogeneity at the air velocity of 0.5 m s-1 was low and then increased at the air velocity of 1 m s-1. Finally, at the air velocity of 1.3 m s-1, it was declined. The overall results illustrate that the applied methodology in this research, which explains unsteady heat transfer in the cooling process, can be performed in pomegranate or similarly shaped fruits.

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Thompson J F, Mitchel F G, Rumsey T R, Kasmire R F & Crisosto C H (1998). Commercial cooling of fruits, vegetables, and flowers. University of California, Agriculture and Natural Resources, Davis, DANR Publication 21567
Ngcobo M E K, Delele M A, Opera U L & Meyer C J (2013). Performance of multi-packaging for table grapes based on airflow, cooling rates and fruit quality. Journal of Food Engineering 116: 613-621
Lindsay R T, Neale M A & Messer H J M (1983). Ventilation rates for positive ventilation of vegetables in bulk bins. Journal of Agricultural Engineering Research 28(1): 33-44
Lambrinos G, Assimaki H, Manolopoulou H, Sfakiotakis E & Porlimgis J (1997). Air precooling and hydrocooling of Hayward Kiwifruit. Acta Horticulturae 444: 561-566
Kumar R, Kumar A & Murthy U N (2008). Heat transfer during forced air precooling of perishable food products. Biosystems Engineering 99: 228-233
Kader A A (2002). Posthaevest technology of horticultural crops. Cooperative Extension of University of California, Division of Agricultural and Natural Resources, University of California, Davis, CA, Publication No. 3311
Henry F E & Bennett A H (1973). Hydraircooling vegetables products in unit loads. Transactions of the ASAE 16(40): 731-739
Hass E, Felsenstein G, Shitzer A & Manor G (1976). Factors affecting resistance to airflow through packed fresh fruit. ASHRAE Transactions 82(2): 548-554
Guillou R (1960). Forced air fruit cooling Transactions of the ASAE 3(2): 16-18
Goyette B, Vigneault C, Panneton B & Raghavan G S V (1996). Method to evaluate the average temperature at the surface of horticultural crop. Canadian Agricultural Enigineering 38(4): 291-295
Golob P, Farrell G & Orchard G E (2002). Crop Postharvest Science and Technology, Principles and Practices. Volume 1. Blackwell Publishing Company, Oxford, UK, pp. 554
Ginsburg L, Combrink J C & Truter A B (1978). Long and short term storage of table grapes. International Journal of Refrigeration 1(3): 137-142
Fadavi A, Barzegar M & Azizi M H (2006). Determination of fatty acids and total lipid content in oilseed of 25 pomegranates varities grown in Iran. Journal of Food Composition Analysis 19: 676-680
Emond J P, Mercier F, Sadfa S O, Bourre M & Gakwaya A (1996). Study of parameters affecting cooling rate and temperature distribution in forced air precooling of strawberry. Transactions of the ASAE 39(6): 2185- 2191
Dincer I & Akaryildiz E (1993). Transient temperature distributions within spherical products with internal heat generation and transpiration. International Journal of Heat and Mass Transfer 36: 1998-2003
Dincer I (1995). Airflow precooling of individual grapes. Journal of Food Engineering 26: 243-249
Dennis C (1984). Effect of storage and distribution conditions on the quality of vegetables. Acta Horticulturae 163: 85-104
Dehghannya J, Ngadi M &Vigneault C (2011). Mathematical modeling of airflow and heat transfer during forced convection cooling of produce considering various package vent areas. Food Control 22: 1393-1399
Castro L R, Vigneault C & Cortez L A B (2005). Cooling performance of horticultural produce in containers with peripheral openings. Postharvest Biology and Technology 38: 254-261
Castro L R, Vigneault C & Cortez L A B (2004). Effect of container opening area on air distribution during precooling of horticultural produce. Transactions of the ASAE 47(6): 2033-2038
Brosnan T & Sun D (2001). Precooling techniques and applications for horticultural products-a review. International Journal of Refrigeration 32: 154-170
Baird C D & Gaffney J J (1976). A numerical procedure for calculating heat transfer in bulk loads of fruits or vegetables. ASHRAE Transactions 82(2): 525-540