Heating and ventilation of the contemporary warehouse complexes

Transcription

1 Heating and ventilation of the contemporary warehouse complexes Е. Shilkrot, Ph.D.,P.E., Head of the Laboratory A. Strongin, Ph.D.,P.E., Technical Director I. Agafonova, P.E., Head of the Designer Department The Central Research Institute for Industrial Buildings, Scientific Production Venture Termek, Moscow, Russia Corresponding INTRODUCTION Cargo handling industry is an important part of the economy. Construction of warehouse complexes utilizing the most modern storage, cargo reception and dispatch technologies is rapidly developing now. In OJSC NPO Termek and OJSC TSNIIPromzdaniy designed and installed heat and ventilation systems for industrial & trade complex Sherland, where the warehouse area is m 2. Figure 1. Industrial & Trade Complex Sherland. METHODS The complex is situated in the vicinity of Sheremetyevo-1 airport, 8 kilometers off the Moscow Ring Road. Warehouse facilities of the complex represent dry heated premises and are provided with the up-to-date equipment. Automated system of stock control allows for

2 high dynamic cargo handling at all stages of the logistic chain from cargo receipt into the warehouse up to its dispatch. All warehouses are equipped with six level rack structures, intra-depot equipment, automated computerized system of stocking activity as well as with monitoring, control and alarm systems, etc. Warehouse premise block represents a single-store, four aisle blocked building shown on Figure 2. Each aisle contains rack storage. Basic specification of each warehouse is given in Table 1. Figure 2. SHERLAND Rack Storage Complex. Layout. The main requirement to the air parameters inside the warehouses is a uniform air temperature distribution in the plan and, especially, throughout the height. Analyses of eventual heating schemes and systems of the rack storages demonstrated that the most rational heating system is a combined heating system, which utilizes local heating registers placed close to the floor alongside the walls and a hot-air heating system with intensive air baffling in the space of the premise. Main heating load comes to the hot-air heating. A hot-air heating system having deflecting nozzles is supported by a perimeter hot-water heating system with heat registers. Additional heating system was provided to prevent cooling of wall-adjacent zones. As the racks are placed virtually right up to the walls it was impossible to supply the hot air into the wall adjacent zone. Table 1. Basic Specification of Industrial & Trade Complex Sherland Warehouse Premises. Pos. PremiseWarehouse No: Dimensions a*b*h, m Area, А, 1000 m² Volume, V, 1000 m³ Rack Space, Vrack, 1000 m³ *56* , !08*56* *56* *56* Hot-air heating system with deflecting nozzles presented at Figure 3 [1] is a modification of the widely used «Direvent» system [2] and provides for virtually uniform air temperature distribution throughout the height of the serviced premises. The system enables to provide an efficient heating at minimized consumption of the air supplied by the nozzles at high velocity and with a considerable temperature differential to secure specified microclimate parameters

3 in the working area. The deflecting nozzles are placed between the racks in the upper zone of the premise and supply the hot air vertically down towards the working zone. Energy efficiency of the system with the deflecting nozzles is secured by a uniform air temperature distribution throughout the height and by elimination of the premises upper zone overheating. Figure 3. Outline of the Air Heating System with Deflecting Nozzles. Table 2 presents the heat load design results for the heating and ventilation systems of the storage premises. Table 2. Calculated Heat Load on the Heating and Ventilation Systems of Industrial & Trade Complex Sherland Warehouse Storage Premises. Pos Premise tн, t в, Heat Consumption, kwh Ware house С* С** Hot- Ventilation Hot-Air Total No Water Heating *** Heating * Outside air temperature; ** Inside air temperature; *** Heat consumption for ventilation is designed at the assumption of a single air renewal in the premise space portion having the height of 6 m. Each warehouse is equipped with two forced ventilation units placed at the mezzanine floors. The forced ventilation installations contain air mixing chambers with valves on both outer and recycle air ducts, which allows for control of outer and recycle air ratio in the course of the operation. During non-heating season the outside air only is supplied into the warehouse in the ventilation mode. During transitional period and heating season the flow of the outside air is decreasing in the heating mode combined with the ventilation depending on the outside air

4 temperature and cargo storage conditions. The forced ventilation units are equipped with multi-speed electrical motors, which enable to provide quantitative adjustment of the systems and secure their high energy efficiency. Removal of the exhaust air form the warehouse is natural via exhaust shafts on the roof combined with the smoke removal shafts. Air ducts of the forced ventilation system are laid down in the roof-truss space alongside the passageways between the racks. Height from the inlet nozzle edge to the floor of the premise is 13.5 m. Air ducts networks are combined in pairs by a bypass duct, which allows for 50% hot-air heating back-up in each warehouse. Diagram of the warehouse hot air heating system is presented at Figure 4. Figure 4. Diagram of the Warehouse Hot Air Heating System. Design of the hot-air heating system with deflecting nozzles is executed in conformity with Recommendations for Design of Heating and Ventilation Systems with Deflecting Nozzles [3]. When designing the air distributing system we have accepted the following provisions as criteria: Minimal number of nozzles, which was provided by a maximal air supply velocity; Maximal supplied air temperature, which provided minimal consumption of the fresh air; Minimal deviations of air temperature and velocity in the working zone during the heating season under fresh air temperature variations. Design results are presented in Table 3.

5 Table 3. Design Results of the System with Deflecting Nozzles Pos. Premise Δt 0, С d 0, m LΣ, m³/h V 0, m/s L nozzle, m³/h n, off Cell Width, m *) H, m Х max, m t н = -28 C K н V w.z., m/s 1 Warehouse No Warehouse No Warehouse No Warehouse No The following notations are used in the Table (Respectively): Δt 0 Temperature difference between the fresh air and the air inside the premise; d 0 Nozzle diameter; L Σ Total air consumption for the system; V 0 Exhaust air velocity; L nozzle Air flow rate through the nozzle; H Geometry parameter of the jet; Х max Jet range capability; K н Jet non-isothermic factor; V w.z Air velocity in the working zone. Width of the cell, where the air jet is developing that is coming out of the nozzle was selected having in view the requirement to provide a uniform air temperature and velocity distribution in the zone to be serviced and to provide the jet development without its cross-sectional constraint. Installation and commissioning works were conducted in Air temperature and velocity were measured at the jet discharge spot and in the working zone alongside the fresh air jet in warehouse No.4 in the course of the commissioning works. At the moment of measuring the outside air temperature was t в = С; air discharge velocity from the nozzle and its temperature was respectively: V m/s; t 0 = 17.6 С. The measurements proved that: Air temperature throughout the warehouse height and working zone area is virtually constant (t в = С); Air velocity in the working zone does not exceed 0.35 m/s; Air velocity distribution alongside the jet axis is close to the design one (Figure 5).

6 Figure 5. Air Velocity Distribution alongside the Jet Axis. THE CONCLUSION Utilization of the hot-air heating system combined with ventilation that is equipped with the qualitative and quantitative control and with air supply by the deflecting nozzles is perspective for large rack-store warehouses. REFERENCES 1. M.I.Grimitlin, A.M. Zhivov, M.I.Ponchek, E.O.Shilkrot Air Supply in the premises by heat and ventilation systems with deflecting nozzles. In the book Air Distribution News/ Seminar Materials, Moscow A Method and a Device for Ventilation. The BRD patent No Applicant AB Svenska Flaktfabriken, Recommendations for design of heat and ventilation systems with deflecting nozzles. TSNIIpromzdaniy, LenPSP, LenVNIIOT, Мoscow 1984.