Soğuk Hava Depolarında Talep Kontrollü Buz Çözme (Defrost) Uygulamaları
Soğuk depolarda evaporatörler donma noktasının altındaki sıcaklıklarda çalışırken, yüzeylerinde kar birikerek soğutma kapasitesini ve etkinliğini azaltır. Karlanmayı gidermek, kapasite ve verimliliği geri kazanmak için evaporatördeki bu kar evaporatöre çeşitli yöntemler ile ısı ekleyerek çözülür. Bu ısıtma işleminde, evaporatöre verilen ısının ancak %25 ila %35 oranındaki kısmı karın erimesine, kalan diğer %65 ila %75’lik kısmı ise iç ortama verilir. Ayrıca buz çözme işlemi zamana bağlı olarak yapıldığında çoğunlukla yüzeylerde yeterli kar birikimi olmadan sistem buz çözme döngüsüne geçer. Bu da iç ortamda istenmeyen sıcaklık artışlarına ve enerji kayıplarına yol açar. Günümüzde mevcut buz çözme yöntemleri çok fazla değişmemekle birlikte kontrol stratejileri çok gelişmiş olup talep kontrollü, adaptif, yapay zekâ destekli buz çözme kontrol yöntemleri geliştirilmiştir. Bu kontrol stratejilerinin temelinde kar birikimini doğrudan ve dolaylı olarak ölçen ve dolayısıyla buz çözme talebini algılayan teknolojiler bulunmaktadır. Bu çalışmada evaporatörlerde karlanma nedenleri açıklanmış, geleneksel buz çözme yöntemleri üzerinde ayrıntılı durulmuştur. Son bölümde talep kontrollü buz çözme kontrol stratejileri ayrıntılı olarak incelemiştir
Demand Controlled Defrost Applications inCold Rooms
While evaporators are operating at temperatures below freezing in cold storages, frost accumulates on their surfaces , reducing the cooling capacity and efficiency. To remove the frost and restore capacity and efficiency, this frost in the evaporators is solved by adding heat to the evaporator with various methods. In this heating process, only 25% to 35% of the heat given to the evaporator is given to the ice to melt and the remaining 65% to 75% is given to the indoor environment. In addition, when the defrosting process is carried out depending on the time, the system often goes into a defrost cycle without sufficient frost accumulation on the surfaces. This leads to undesirable temperature increases and energy losses in the indoor environment, although the current defrosting methods do not change much, control strategies are very advanced and demand-controlled, adaptive, artificial intelligence-assisted defrosting control methods have been developed. At the heart of these control strategies are technologies that directly and indirectly measure ice build-up and thus perceive defrost demand. In this study, the reasons for icing in evaporators are explained and traditional defrosting methods are discussed in detail. In the last section, demand controlled defrosting control strategies are examined in detail.
___
- [1] https://www.industrialcontrolsonline.com/ training/online/demand-defrost (11.02.2020)
- [2] Kenneth S. Franklin, C.M., Director of Service, Hussmann Corporation Defrosting Methods, RSES (Refrigeration Service Engineering Society) Service Application Manual SAM Chapter 620-49 Section P1, 2001.
- [3] https://www.hpacmag.com/features/refrigeration-defrost/ (12.03.2020 tarihinde erişildi)
- [4] https://www.pge.com/en/mybusiness/save/ smbblog/article/RefrigerationControls.page
- [5] Jarrett, J.H., “A New Demand Defrost Control for Domestic Forced Draft Refrigerator/ Freezers and Freezers”, IEEE Transactions on Industry Applications IA-8, no. 3 (1972): 356- 364.
- [6] https://www.johnsoncontrols.com/building-automation-and-controls/hvac-controls/ control-sensors/differential-pressure-transmitter
- [7] Hahn, T.W., and J.D. Broyles, “Electronic Refrigeration Defrost Control”, Report of Performance. “IEEE Transaction on Industry and General Applications 4, no. 1 (1968): 114-119.
- [8] https://www.epluse.com/en/products/air-velocity-instrumentation/transmitters-for-air-velocity-measurement/ee660/ (14.03.2020 tarihinde erişildi)
- [9] Danfoss, Controller for Temperature ControlEKC 102, Manual RS8DY802 © Danfoss 08- 2010.
- [10] Lawrence, J.M.W., Defrost Control Method and Apparatus. United States of America Patent 6,718,778. April 13, 2004.
- [11] Lawrance, J.M.W. and J.A. Evans, “Refrigerant Flow Instability as a Means to Predict the Need for Defrosting the Evaporator in a Retail Display Freezer Cabinet”, International Journal of Refrigeration 31, no. 1 (2008): 107-112.
- [12] K. Qu, S. Komori e Y. Jiang, “Local Variation of Frost Layer Thickness and Morphology”, International Journal of Thermal Sciences, vol. 45, pp. 116-123, 2006.
- [13] M. Kandula, “Frost Growth and Densification on a Flat Surface in Laminar Flow With Variable Humidity”, International Communications in Heat and Mass Transfer, vol. 39, pp. 1030- 1034, 2012.
- [14] Y. Ge, Y. Sun, W. Wang, J. Zhu, L. Li e J. Liu, F,” International journal of refrigeration, vol. 66, pp. 133-144, 2016.
- [15] W. Wang, J. Xiao, Y. Feng, Q. Guo e L. Wang, “Characteristics of an Air Source Heat Pump With Novel Photoelectric Sensors During Periodic Frostedefrost Cycles”, Applied Thermal Engineering, vol. 50, pp. 117-186, 2013.
- [16] J. Ge, L. Ye e J. Zou, “A Novel Fiber-Optic Ice Sensor Capable of Identifying Ice Type Accurately”, Sensors and Actuators A: Physical, vol. 175, pp. 35-42, 2012.
- [17] A. Toriano, E. Pasero e L. Mesin, “New System for Detecting Road Ice Formation”, IEEE Transactions on Instrumentation and Measurement, vol. 60, no 3, pp. 1091-1101, 2011.
- [18] S. Roy, A. Izad, R. G. DeAnna e M. Mehregany, “Smart Ice Detection Systems Based on Resonant Piezoelectric Transducers”, Sensors and Actuators A, vol. 69, pp. 243-250, 1998.
- [19] https://shop.hbproducts.dk/defrost-on-demand-sensor-mk2/135/
- [20] https://www.hbproducts.dk/images/manualer/ HBDF-MK2/HBDF-MK2_Instruction-manual-013-UK.pdf
- [21] Allard, John, and Robert Heinzen, “Adaptive Defrost”, IEEE Transactions on Industry Applications 24, no. 1 (1988): 39-42.
- [22] Hindmond, J., and H. Henderson, Refrigerated Display Case Demand Defrost Controller: Field Demonstration Results, TR-112121, Palo Alto, CA: Electric Power Research Institute, 1998.
- [23] Datta, Debarati, and Savvas Tassou, “Implementation of a Defrost on Demand Control Strategy on a Retail Display Cabinet”, New Technologies in Commercial Refrigeration, Urbana, IL: International Institute of Refrigeration, 2002. 218-226.
- ISSN: 1300-3399
- Yayın Aralığı: Yılda 6 Sayı
- Başlangıç: 1993
- Yayıncı: TMMOB MAKİNA MÜHENDİSLERİ ODASI