سردخانه فریونی یا سردخانه آمونیاکی
درصورتیکه قصد تاسیس یک سردخانه نگهداری مواد غذایی را دارید و تفاوتها و مزایا و معایب انواع سردخانه ها را نمیدانید این مقاله میتواند برای شما مفید باشد
مزایای سردخانه آمونیاکی:
– دارای بالاترین اثر تبرید را بین مبردها (آمونیاک)
– دوستدار محیط زیست
– ارزان بودن مبرد سردخانه آمونیاکی (قیمت هر کیلوگرم R22، دو نیم برابر آمونیاک و هر کیلوگرم R134، 7 برابر آمونیاک است)
– بوی شدید آمونیاک(تشخیص نشتی آسان)
– هزینه عملیاتی پایین برای سردخانههای بزرگ (چرخه آمونیاکی 10 تا 20 درصد هزینه کمتری نسبتبه چرخه گاز R22 دارد.)
– ضریب عملکرد بالاتر سیکل(ضریب عملکرد سیکل آمونیاکی حدود 10% بالاتر از ضریب عملکرد سیکل فریونی است. )
– انتقال حرارت بالاتر آمونیاک(3.5 تا4 برابر برای کندانسور و 1.5 تا 2 برابر برای اواپراتور) که منجربه ارزانتر شدن اواپراتور و کندانسور میشود.)
– نیاز به لوله با قطر کمتر(از آنجایی که لوله کشی سهم پایینی از هزینههای سردخانه را دربر دارد، این مورد برای سردخانه های بزرگ مزیت محسوب میشود)
– عدم اختلاط آمونیاک با روغن(که برای سیستمهای صنعتی بزرگ مزیت محسوب میشود)
معایب سردخانه آمونیاکی:
– سمی بودن آمونیاک
– قابل اشتعال بودن آمونیاک (شرایط خاص)
– نیاز به بازرسی مداوم بهمنظور جلوگیری از نشت وسیع گاز
– قوانین ایمنی سخت گیرانه(تجربه نشان میدهد که این عامل مهمترین عامل موثر برای انتخاب سیستم فریونی بهجای آمونیاکی در سراسر دنیا است.)
– کارکرد آمونیاک با فشار پایینتر از فشار جو درون خط کم فشار (که هنگام سوراخ شدن لولهها باعث مکیدن هوا و آب بهداخل و تشدید خوردگی میشود)
– حساسیت شدید بهحضور آب (در حضور آب قطعات غیرآهنی مانند مس و برنج بهشدت توسط آمونیاک خورده میشوند.)
– عدم بازدهی مناسب برای سردخانه کوچک
مزایای سردخانه فریونی:
– غیر سمیبودن مبرد
– غیر قابل اشتعال بودن مبرد
– قوانین ایمنی آسان درخصوص سردخانه های فریونی(به این علت که خطر جانی و مسمومیت ندارند)
– مناسب برای سردخانه های کوچک و متوسط
معایب سردخانه فریونی:
– ناسازگاری گازهای فریونی با محیط زیست
– گران بودن گازهای فریونی
– بدون بو(عدم تشخیص نشتی) بودن گاز فریونی
– محدود شدن و عوض شدن مبردهای مجاز(البته این مورد با توجه به روز شدن محصولات تولیدی این حوزه مانعی ایجاد نمیکند)
– اکثر منابع ذکر کردهاند که استفاده از آمونیاک برای سردخانه های بزرگ یا صنایع یخ سازی مناسبتر است. این مطلب با بررسی سردخانه هایی که داخل کشور فعال هستند نیز قابل مشاهده است. مشاهده میشود که تمام سالنهای یخ سازی و سردخانه های معظم با سیستم آمونیاکی مشغول به فعالیت هستند و تمام سردخانه های کوچک و متوسط(تا ظرفیت 800 پالت 100 x 120 سانتیمتری) با گاز R22 مشغول به کارند.
– استفاده از سردخانه آمونیاکی نیاز به جوشکاری دقیق و با کیفیت بالای لولهها دارد. درصورتیکه کنترل دقیق کیفیت اتصالات حین تولید و حین کار هزینه بالایی برای مجموعه شما به بار میآورد، بهتر است که سردخانه خود را با گاز R22 یا R404 طراحی و راه اندازی کنید. زیرا درصورت عدم کنترل کیفیت دقیق نصب لولهکشی سردخانه آمونیاکی، هزینههای مالی و جانی فراوانی را در آینده متحمل خواهید شد. حال آنکه سردخانه فریونی از این لحاظ بسیار امنتر است.
– میدانیم سردخانه آمونیاکی ضریب عملکرد بالاتر و در نتیجه مصرف برق پایین تری دارد. این مساله در کشور ما با توجه به ارزان بودن انرژی کمک زیادی به سردخانهداران نمیکند. زیرا با توجه به هزینه تعمیرات و نگهداری بالاتری که سردخانه آمونیاکی دارد این هزینه بهراحتی جبران میشود.
A warehouse is a building for storing goods. Warehouses are used by manufacturers, importers, exporters, wholesalers, transport businesses, customs, etc. They are usually large plain buildings in industrial parks on the outskirts of cities, towns or villages.
They usually have loading docks to load and unload goods from trucks. Sometimes warehouses are designed for the loading and unloading of goods directly from railways, airports, or seaports. They often have cranes and forklifts for moving goods, which are usually placed on ISO standard pallets loaded into pallet racks. Stored goods can include any raw materials, packing materials, spare parts, components, or finished goods associated with agriculture, manufacturing, and production. In India, a warehouse may be referred to as a godown.
- 4Recent trends
- 6See also
- 8Further reading
- 9External links
A warehouse can be defined functionally as a building in which to store bulk produce or goods (wares) for commercial purposes. The built form of warehouse structures throughout time depends on many contexts: materials, technologies, sites, and cultures.
In this sense, the warehouse postdates the need for communal or state-based mass storage of surplus food. Prehistoric civilizations relied on family- or community-owned storage pits, or ‘palace’ storerooms, such as at Knossos, to protect surplus food. The archaeologist Colin Renfrew argued that gathering and storing agricultural surpluses in Bronze Age Minoan ‘palaces’ was a critical ingredient in the formation of proto-state power.
The need for warehouses developed in societies in which trade reached a critical mass requiring storage at some point in the exchange process. This was highly evident in ancient Rome, where the horreum (pl. horrea) became a standard building form. The most studied examples are in Ostia, the port city that served Rome. The Horrea Galbae, a warehouse complex on the road towards Ostia, demonstrates that these buildings could be substantial, even by modern standards. Galba’s horrea complex contained 140 rooms on the ground floor alone, covering an area of some 225,000 square feet (21,000 m²). As a point of reference, less than half of U.S. warehouses today are larger than 100,000 square feet (9290 m²).
The need for a warehouse implies having quantities of goods too big to be stored in a domestic storeroom. But as attested by legislation concerning the levy of duties, some medieval merchants across Europe commonly kept goods in their large household storerooms, often on the ground floor or cellars.  An example is the Fondaco dei Tedeschi, the substantial quarters of German traders in Venice, which combined a dwelling, warehouse, market and quarters for travellers.
From the middle ages on, dedicated warehouses were constructed around ports and other commercial hubs to facilitate large-scale trade. The warehouses of the trading port Bryggen in Bergen, Norway (now a World Heritage site), demonstrate characteristic European gabled timber forms dating from the late middle ages, though what remains today was largely rebuilt in the same traditional style following great fires in 1702 and 1955.
During the industrial revolution, the function of warehouses evolved and became more specialised. Always a building of function, in the past few decades warehouses have adapted to standardisation, mechanisation, technological innovation and changes in supply chain methods.
The mass production of goods launched by the industrial revolution of the 18th and 19th centuries fuelled the development of larger and more specialised warehouses, usually located close to transport hubs on canals, at railways and portside. Specialisation of tasks is characteristic of the factory system, which developed in British textile mills and potteries in the mid-late 1700s. Factory processes speeded up work and deskilled labour, bringing new profits to capital investment.
Warehouses also fulfill a range of commercial functions besides simple storage, exemplified by Manchester’s cotton warehouses and Australian wool stores: receiving, stockpiling and despatching goods; displaying goods for commercial buyers; packing, checking and labelling orders, and dispatching them.
The utilitarian architecture of warehouses responded fast to emerging technologies. Before and into the nineteenth century, the basic European warehouse was built of load-bearing masonry walls or heavy-framed timber with a suitable external cladding. Inside, heavy timber posts supported timber beams and joists for the upper levels, rarely more than four to five stories high.
A gabled roof was conventional, with a gate in the gable facing the street, rail lines or port for a crane to hoist goods into the window-gates on each floor below. Convenient access for road transport was built-in via very large doors on the ground floor. If not in a separate building, office and display spaces were located on the ground or first floor.
Technological innovations of the early 19th century changed the shape of warehouses and the work performed inside them: cast iron columns and later, moulded steel posts; saw-tooth roofs; and steam power. All (except steel) were adopted quickly and were in common use by the middle of the 19th century.
- 1. Strong, slender cast iron columns began to replace masonry piers or timber posts to carry levels above the ground floor. As modern steel framing developed in the late 19th century, its strength and constructability enabled the first skyscrapers. Steel girders replaced timber beams, increasing the span of internal bays in the warehouse.
- 2. The saw-tooth roof brought natural light to the top story of the warehouse. It transformed the shape of the warehouse, from the traditional peaked hip or gable to an essentially flat roof form that was often hidden behind a parapet. Warehouse buildings now became strongly horizontal. Inside the top floor, the vertical glazed pane of each saw-tooth enabled natural lighting over displayed goods, improving buyer inspection.
- 3. Hoists and cranes driven by steam power expanded the capacity of manual labour to lift and move heavy goods.
Two more new power sources, hydraulics, and electricity, re-shaped warehouse design and practice at the end of the 19th century and into the 20th century.
- 1. Public hydraulic power networks were constructed in many large industrial cities around the world in the 1870s-80s, exemplified by Manchester. They were highly effective to power cranes and lifts, whose application in warehouses served taller buildings and enabled new labour efficiencies.
- 2. Public electricity networks emerged in the 1890s. They were used at first mainly for lighting and soon to electrify lifts, making possible taller, more efficient warehouses. It took several decades for electrical power to be distributed widely throughout cities in the western world.
20th-century technologies made warehousing ever more efficient. Electricity became widely available and transformed lighting, security, lifting and transport from the 1900s. The internal combustion engine, developed in the late 19th century, was installed in mass-produced vehicles from the 1910s. It not only reshaped transport methods but enabled many applications as a compact, portable power plant, wherever small engines were needed.
The forklift truck was invented in the early 20th century and came into wide use after World War II. Forklifts transformed the possibilities of multi-level pallet racking of goods in taller, single-level steel-framed buildings for higher storage density. The forklift, and its load fixed to a uniform pallet, enabled the rise of logistic approaches to storage in the later 20th century.
Warehouses are generally considered industrial buildings and are usually located in industrial districts or zones (such as the outskirts of a city). LoopNet categorizes warehouses using the “industrial” property type. Craftsman Book Company’s 2018 National Building Cost Manual lists “Warehouses” under the “Industrial Structures Section.” In the UK, warehouses are classified under the Town and Country Planning Act 1990 as the industrial category B8 Storage and distribution.
These displayed goods for the home trade. This would be finished goods- such as the latest cotton blouses or fashion items. Their street frontage was impressive, so they took the styles of Italianate Palazzi.
Richard Cobden‘s construction in Manchester’s Mosley Street was the first palazzo warehouse. There were already seven warehouses on Portland Street when they commenced building the elaborate Watts Warehouse of 1855, but four more were opened before it was finished.
Cool warehouses and cold storage
Cold storage preserves agricultural products. Refrigerated storage helps in eliminating sprouting, rotting and insect damage. Edible products are generally not stored for more than one year. Several perishable products require a storage temperature as low as −25 °C.
Cold storage helps stabilize market prices and evenly distribute goods both on demand and timely basis. The farmers get the opportunity of producing cash crops to get remunerative prices. The consumers get the supply of perishable commodities with lower fluctuation of prices.
Ammonia and Freon compressors are commonly used in cold storage warehouses to maintain the temperature. Ammonia refrigerant is cheaper, easily available, and has a high latent heat of evaporation, but it is also highly toxic and can form an explosive mixture when mixed with fuel oil. Insulation is also important, to reduce the loss of cold and to keep different sections of the warehouse at different temperatures.
There are two main types of refrigeration system used in cold storage warehouses: vapor absorption systems (VAS) and vapor-compression systems (VCS). VAS, although comparatively costlier to install, is more economical in operation.
The temperature necessary for preservation depends on the storage time required and the type of product. In general, there are three groups of products, foods that are alive (e.g. fruits and vegetables), foods that are no longer alive and have been processed in some form (e.g. meat and fish products), and commodities that benefit from storage at controlled temperature (e.g. beer, tobacco).
Location is important for the success of a cold storage facility. It should be in close proximity to a growing area as well as a market, be easily accessible for heavy vehicles, and have an uninterrupted power supply.
These catered for the overseas trade. They became the meeting places for overseas wholesale buyers where printed and plain could be discussed and ordered. Trade in cloth in Manchester was conducted by many nationalities.
Behrens Warehouse is on the corner of Oxford Street and Portland Street. It was built for Louis Behrens & Son by P Nunn in 1860. It is a four-storey predominantly red brick build with 23 bays along Portland Street and 9 along Oxford Street. The Behrens family were prominent in banking and in the social life of the German Community in Manchester. 
The main purpose of packing warehouses was the picking, checking, labelling and packing of goods for export. The packing warehouses: Asia House, India House and Velvet House along Whitworth Street in Manchester were some of the tallest buildings of their time.
Warehouses were built close to the major stations in railway hubs. The first railway warehouse to be built was opposite the passenger platform at the terminus of the Liverpool and Manchester Railway. There was an important group of warehouses around London Road station (now Piccadilly station).In the 1890s the Great Northern Railway Company’s warehouse was completed on Deansgate: this was the last major railway warehouse to be built.
The London Warehouse Picadilly was one of four warehouses built by the Manchester, Sheffield and Lincolnshire Railway in about 1865 to service the new London Road Station. It had its own branch to the Ashton Canal. This warehouse was built of brick with stone detailing. It had cast iron columns with wrought iron beams.
All these warehouse types can trace their origins back to the canal warehouses which were used for trans-shipment and storage. Castlefield warehouses are of this type- and important as they were built at the terminus of the Bridgewater Canal in 1761.
A customised storage building—a warehouse—enables a business to stockpile goods, eg, to build up a full load prior to transport, or hold unloaded goods before further distribution, or store goods like wine and cheese that require maturation. As a place for storage, the warehouse has to be secure, convenient, and as spacious as possible, according to the owner’s resources, the site and contemporary building technology. Before mechanised technology developed, warehouse functions relied on human labour, using mechanical lifting aids like pulley systems.
Storage and shipping systems
Some of the most common warehouse storage systems are:
- Pallet racking including selective, drive-in, drive-thru, double-deep, pushback, and gravity flow
- Cantilever racking uses arms, rather than pallets, to store long thin objects like timber.
- Mezzanine adds a semi-permanent story of storage within a warehouse
- Vertical Lift Modules are packed systems with vertically arranged trays stored on both sides of the unit.
- Horizontal Carousels consist of a frame and a rotating carriage of bins.
- Vertical Carousels consisting of a series of carriers mounted on a vertical closed-loop track, inside a metal enclosure.
A “piece pick” is a type of order selection process where a product is picked and handled in individual units and placed in an outer carton, tote or another container before shipping. Catalog companies and internet retailers are examples of predominantly piece-pick operations. Their customers rarely order in pallet or case quantities; instead, they typically order just one or two pieces of one or two items. Several elements make up the piece-pick system. They include the order, the picker, the pick module, the pick area, handling equipment, the container, the pick method used and the information technology used. Every movement inside a warehouse must be accompanied by a work order. Warehouse operation can fail when workers move goods without work orders, or when a storage position is left unregistered in the system.
Material direction and tracking in a warehouse can be coordinated by a Warehouse Management System (WMS), a database driven computer program. Logistics personnel use the WMS to improve warehouse efficiency by directing pathways and to maintain accurate inventory by recording warehouse transactions.
Automation and optimization
Some warehouses are completely automated, and require only operators to work and handle all the task. Pallets and product move on a system of automated conveyors, cranes and automated storage and retrieval systems coordinated by programmable logic controllers and computers running logistics automation software. These systems are often installed in refrigerated warehouses where temperatures are kept very cold to keep the product from spoiling. This is especially true in electronics warehouses that require specific temperatures to avoid damaging parts. Automation is also common where land is expensive, as automated storage systems can use vertical space efficiently. These high-bay storage areas are often more than 10 meters (33 feet) high, with some over 20 meters (65 feet) high. Automated storage systems can be built up to 40m high.
For a warehouse to function efficiently, the facility must be properly slotted. Slotting addresses which storage medium a product is picked from (pallet rack or carton flow), and how they are picked (pick-to-light, pick-to-voice, or pick-to-paper). With a proper slotting plan, a warehouse can improve its inventory rotation requirements—such as first in, first out (FIFO) and last in, first out (LIFO)—control labor costs and increase productivity.
Pallet racks are commonly used to organize a warehouse. It is important to know the dimensions of racking and the number of bays needed as well as the dimensions of the product to be stored. Clearance should be accounted for if using a forklift or pallet mover to move inventory.
Modern warehouses commonly use a system of wide aisle pallet racking to store goods which can be loaded and unloaded using forklift trucks.
Traditional warehousing has declined since the last decades of the 20th century, with the gradual introduction of Just In Time techniques. The JIT system promotes product delivery directly from suppliers to consumer without the use of warehouses. However, with the gradual implementation of offshore outsourcing and offshoring in about the same time period, the distance between the manufacturer and the retailer (or the parts manufacturer and the industrial plant) grew considerably in many domains, necessitating at least one warehouse per country or per region in any typical supply chain for a given range of products.
Recent retailing trends have led to the development of warehouse-style retail stores. These high-ceiling buildings display retail goods on tall, heavy-duty industrial racks rather than conventional retail shelving. Typically, items ready for sale are on the bottom of the racks, and crated or palletized inventory is in the upper rack. Essentially, the same building serves as both a warehouse and retail store.
Another trend relates to vendor-managed inventory (VMI). This gives the vendor the control to maintain the level of stock in the store. This method has its own issue that the vendor gains access to the warehouse.
Large exporters and manufacturers use warehouses as distribution points for developing retail outlets in a particular region or country. This concept reduces end cost to the consumer and enhances the production sale ratio.
Cross-docking is a specialised type of distribution center (DC) in that little or no inventory is stored and product is received, processed (if needed) and shipped within a short timeframe. As in warehousing, there are different types of cross-docks.
Reverse logistics is another type of warehousing that has become popular for environmental reasons. The term refers to items that are going from the end user back to the distributor or manufacturer.
There are few non-profit organizations which are focused on imparting knowledge, education and research in the field of warehouse management and its role in the supply chain industry. The Warehousing Education and Research Council (WERC) and International Warehouse Logistics Association (IWLA) in Illinois, United States. They provide professional certification and continuing education programs for the industry in the country. The Australian College of Training have government funded programs to provide personal development and continuation training in warehousing certs II – V (Diploma), they operate in Western Australia online and face to face, or Australia wide for online only courses.