Optimization of recirculating laminar air flow in operating room air conditioning systems
The laminar flow air-conditioning system with 100% fresh air is used in almost all operating rooms without discrimination in Turkey. The laminar flow device which is working with 100% fresh air should be absolutely used in Type 1A operating rooms. However, there is not mandatory to use of 100% fresh air for Type 1B defined as places performed simpler operation. Compared with recirculating laminar flow, energy needs of the laminar flow with 100 % fresh air has been emerged about 40% more than re-circulated air flow. Therefore, when a recirculating laminar flow device is operated instead of laminar flow system with 100% fresh air in the Type 1B operating room, annual energy consumption will be reduced. In this study, in an operating room with recirculating laminar flow, optimal conditions have been investigated in order to obtain laminar flow form by analyzing velocity distributions at various supply velocities by using computational fluid dynamics method (CFD).
[1] Friberg, B., Friberg, S. and Burman L.G., Inconsistent correlation between aerobic bacterial surface and air counts in operating rooms with ultra clean laminar air flows: proposal of a new bacteriological standard for surface contamination. Journal of Hospital Infection, 42, 287-293 (1999).
[2] Deutsches Institut fur Normung (German Institute for Standardization) DIN 1946- 4:2005-02 Heating, ventilation and air conditioning systems in Hospitals.
[3] Woloszyn, M., Virgone, J. and Melen, S., Diagonal air-distribution system for operating rooms: experiment and modeling. Building and Environment, 39, 1171-1178 (2004).
[4] Andersson, A.E., Petzold, M., Bergh, I., Karlsson, J., Eriksson, B.I. and Nilsson, K., Comparison between mixed and laminar airflow systems in operating rooms and the influence of human factors: Experiences from a Swedish orthopedic center. American Journal of Infection Control, 42, 665-669 (2014).
[5] Baskan, O., Speetjens, M.F.M., Metcalfe, G. and Clercx, H.J.H., Experimental and computational study of scalar modes in a periodic laminar flow. International Journal of Thermal Sciences, 96, 102-118, (2015).
[6] Balaras, C.A., Dascalaki, E. and Gaglia, A., HVAC and indoor thermal conditions in hospital operating rooms. Energy and Buildings, 39, 454-470, (2007).
[7] Dascalakia, E.G., Lagoudib, A., Balarasa, C.A. and Gaglia, A.G., Air quality in hospital operating rooms, Building and Environment, 43, 1945-1952, (2008).
[8] Diab-Elschahawi, M., Berger, J., Blacky, A., Kimberger, O., Oguz, R., Kuelpmann, R., Kramer, A. and Assadian, O., Impact of different-sized laminar airflow versus no laminar air flow on bacterial counts in the operating room during orthopedic surgery. American Journal of Infection Control, 39, 25-29, (2011).
[9] Hirsch, T., Hubert, H., Fischer, S., Lahmer, A., Lehnhardt, M., Steinau, H.U., Steinstraesser, L. and Seipp, H.M., Bacterial burden in the operating room: Impact of airflow systems. American Journal of Infection Control, 40, 228-232, (2012).
[10] Nilsson, K.G., Lundholm, R., and Friberg, S., Assessment of horizontal laminar air flow instrument table for additional ultraclean space during surgery. Journal of Hospital Infection, 76, 243-246, (2010).
[11] Ozyogurtcu, G., Mobedi, M. and Ozerdem, B., Economical assessment of different HVAC systems for an operating room: Case study for different Turkish climate regions. Energy and Buildings, 43, 1536-1543, (2011).
[12] Launder, B.E. and Spalding, D.B., Lectures in Mathematical Models of Turbulence, London, England: Academic Press, (1972).
[13] Ansys Fluent 15.0, Theory Guide (2014).