Refrigeration And Air Conditioning Basics Pdf

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refrigeration and air conditioning basics pdf

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Lesson 3. Lesson 5. Effect of change of operation conditions on the working of vapour compression refrigeration plant.

Introduction and Basic Concepts of Refrigeration and Air Conditioning, PDF

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Mechanical Engineering Handbook. Pawan Gupta. Download PDF. A short summary of this paper. Wang, S. Wang 9. The com- bination of these processes is equivalent to the functions performed by air-conditioning. They are often called comfort air-conditioning systems. In manufacturing buildings, air-conditioning systems are provided for product processing, or for the health and comfort of workers as well as processing, and are called processing air-conditioning systems.

Based on their size, construction, and operating characteristics, air-conditioning systems can be classified as the following. Individual Room or Individual Systems. An individual air-conditioning system normally employs either a single, self-contained, packaged room air conditioner installed in a window or through a wall or separate indoor and outdoor units to serve an individual room, as shown in Figure 9.

Space-Conditioning Systems or Space Systems. These systems have their air-conditioning—cooling, heating, and filtration—performed predominantly in or above the conditioned space, as shown in Figure 9. Outdoor air is supplied by a separate outdoor ventilation system. Unitary Packaged Systems or Packaged Systems. These systems are installed with either a single self- contained, factory-assembled packaged unit PU or two split units: an indoor air handler, normally with ductwork, and an outdoor condensing unit with refrigeration compressor s and condenser, as shown in Figure 9.

In a packaged system, air is cooled mainly by direct expansion of refrigerant in coils called DX coils and heated by gas furnace, electric heating, or a heat pump effect, which is the reverse of a refrigeration cycle. Central Hydronic or Central Systems. A central system uses chilled water or hot water from a central plant to cool and heat the air at the coils in an air handling unit AHU as shown in Figure 9. For energy transport, the heat capacity of water is about times greater than that of air.

Central systems are built-up systems assembled and installed on the site. Packaged systems are comprised of only air system, refrigeration, heating, and control systems. Both central and space-conditioning systems consist of the following.

Air Systems. Its function is to condition the air, distribute it, and control the indoor environment according to requirements. The primary equipment in an air system is an AHU or air handler; both of these include fan, coils, filters, dampers, humidifiers optional , supply and return ductwork, supply outlets and return inlets, and controls.

Water Systems. These systems include chilled water, hot water, and condenser water systems. A water system consists of pumps, piping work, and accessories. The water system is sometimes called the water side of a central or space-conditioning system. Central Plant Refrigeration and Heating Systems. The refrigeration system in the central plant of a central system is usually in the form of a chiller package with an outdoor condensing unit.

The refrigeration system is also called the refrigeration side of a central system. A boiler and accessories make up the heating system in a central plant for a central system, and a direct-fired gas furnace is often the heating system in the air handler of a rooftop packaged system.

Control Systems. Control systems usually consist of sensors, a microprocessor-based direct digital controller DDC , a control device, control elements, personal computer PC , and communication network.

Part of the cooled floor area has been counted for both individual and packaged systems. The sum of the floor areas for these three systems therefore exceeds the total cooled area of 57, million ft2. There are two types of air-conditioning projects: design- bid and design-build. A design-bid project separates the design engineering consultant and installation contractors responsibilities.

In a design-build project, the design is also done by the installation contractor. A design-build project is usually a small project or a project having insufficient time to go through normal bidding procedures. Air-conditioning design is a process of selecting the optimum system, subsystem, equipment, and components from various alternatives and preparing the drawings and specifications.

Design determines the basic operating characteristics of a system. After an air-conditioning system is designed and constructed, it is difficult and expensive to change its basic characteristics. The foundation of a successful project is teamwork and coordination between designer, contractor, and operator and between mechanical engineer, electrical engineer, facility operator, architect, and structural engineer.

Field experience is helpful to the designer. Before beginning the design process it is advisable to visit similar projects that have operated for more than 2 years and talk with the operator to investigate actual performance. Initiation of a project by owner or developer 2. Organizing a design team 3. Determining the design criteria and indoor environmental parameters 4. Calculation of cooling and heating loads 5. Selection of systems, subsystems, and their components 6.

Preparation of schematic layouts; sizing of piping and ductwork 7. Preparation of contract documents: drawings and specifications 8. Competitive biddings by various contractors; evaluation of bids; negotiations and modifications 9. Advice on awarding of contract Monitoring, supervision, and inspection of installation; reviewing shop drawings Supervision of commissioning Modification of drawings to the as-built condition; preparation of the operation and maintenance manual Handing over to the property management for operation Design Documents Drawings and specifications are legal documents of a construction contract.

Drawings and specifi- cations complement each other. Drawings should clearly and completely show, define, and present the work. Adequate plan and sectional views should be drawn.

More often, isometric drawings are used to show the flow diagrams for water or the supply, return, and exhaust air. Specifications include the legal contract between the owner and the contractor, installer, or vendor and the technical specifications, which describe in detail what kind of material and equipment should be used and how they are to be installed. It includes 16 divisions. The Mechanical division is divided into the following: Section No.

Title Air Distribution Controls Testing, Adjusting, and Balancing Each section includes general considerations, equipment and material, and field installation.

There are two types of specifications: the performance specification, which depends mainly on the required performance criteria, and the or-equal specification, which specifies the wanted vendor. Spec- ifications should be written in simple, direct, and clear language without repetition.

Computer-Aided Design and Drafting With the wide acceptance of the PC and the availability of numerous types of engineering software, the use of computer-aided drafting CAD and computer-aided design and drafting CADD has increased greatly in recent years.

Drafting software used to reproduce architectural drawings is the foundation of CADD. Automated CAD AutoCAD is the leading personal computer-based drafting tool software used in architectural and engineering design firms.

Both of them convert the single-line duct layout drawn with CAD to two-dimensional 2D double-line drawings with fittings, terminals, and diffusers. Software for piping system design and analysis can also be integrated with CAD. The most widely used software for load calculations and energy analysis is Department of Energy DOE Product categories include selection, configuration, performance, price, and maintenance schedule.

Product manufacturers provide software including data and CAD drawings for their specific product. Federal and local codes must be followed. The designer should be thoroughly familiar with relevant codes. However, for design criteria or performance that has not been covered in the codes, whether the ASHRAE Standard is followed or violated is the vital criterion, as was the case in a recent indoor air quality lawsuit against a designer and contractor.

The lower atmosphere, or homosphere, is composed of moist air, that is, a mixture of dry air and water vapor. Psychrometrics is the science of studying the thermodynamic properties of moist air. It is widely used to illustrate and analyze the change in properties and the thermal characteristics of the air-conditioning process and cycles.

The composition of dry air varies slightly at different geographic locations and from time to time. The approximate composition of dry air by volume is nitrogen, The variation of water vapor has a critical influence on the characteristics of moist air. National Bureau of Standards. According to Nelson et al. Therefore, ideal gas equations are used in the development and calculation of psychrometric formulations in this handbook.

Air-Conditioning and Refrigeration. Mechanical Engineering Handbook

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Site news. Topic outline. Ravi Kumar. Topic 1 Module 1: Fundamentals of refrigeration. Lesson 1. Basic refrigeration cycle and concepts, standard rating of refrigerating machines Page. Quiz 1.

Condens Section 9 — Building Applications. The refrigeration or air conditioning system R transfers heat from a cooler low-energy reservoir to a warmer high-energy reservoir ; There are several heat transfer loops in a refrigeration system as shown in Figure 2. The window and split air conditioners are used for single rooms or small office spaces. Technical Options Committee. Air conditioning and refrigeration. Refrigeration Basics Refrigeration Cycle Refrigeration Basics - continued Basics - continued If a refrigerating system - a window box AC unit removes - or lifts - 12, BTUs per hour from a room and rejects it to the outside air then the unit is said to have the capacity of one ton.

ppt on refrigeration and air conditioning presentation

Flashing lowers the coolant temperature to a saturation temperature at the low-side pressure. What is Heat? The quantity of heat contained in an object or substance is not the same as its intensity of heat.

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Refrigeration cycle, HVAC system basics and refrigerant charging.pdf

Refrigeration and air conditioning solved problems pdf

Compressors , Psychrometry and Applications of Refrigeration and Air Conditioning have been included and updated for students to conceptualise the subject in a complete manner. The chapters consist of various exercises, examples, and multiple illustrations that aid in understanding the subject better. The subject of refrigeration and airconditioning is one of great significance as public focus shifts to food processing and preservation technologies. This highlights the need for professionals well-versed in the basics of this technology. A Textbook Of Refrigeration And Air Conditioning elaborates on the basics of this subject by including discussions on topics like multiple evaporator and compressor systems, simple and compound vapour compression refrigeration systems, air refrigeration cycles and systems, psychrometry, vapour absorption refrigeration and compressor systems, comfort conditions, psychrometry, refrigerants and compressors, cooling load estimation, steam jet refrigeration system, evaporators, condensers, expansion devices, and food preservation including cryogenics, fans, and ducts.

This process is accompanied by an increase in Entropy along with a drop in pressure due to which volume increases and a part of the liquid is vaporized, thus cooling the liquid. Real gases produce a substantial decrease in temperature under certain condition, which corresponds to a certain initial low temperature and high pressure of the gas. Cooling is produced of one junction of two dissimilar metals if a current is passed through them.

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 ВР! - крикнула Соши, усаживаясь за компьютер в задней части комнаты. На стене ожила связанная с компьютером диаграмма. Сьюзан рассеянно подняла на нее глаза, безучастная к царившему вокруг нее безумию. Все в комнате дружно повернули головы. Диаграмма чем-то напоминала бычий глаз. В центре находился красный кружок с надписью БАЗА, вокруг которого располагались пять концентрических окружностей разной толщины и разного цвета. Внешняя окружность была затуманена и казалась почти прозрачной.

Когда его обвиняли в фаворитизме, он в ответ говорил чистую правду: Сьюзан Флетчер - один из самых способных новых сотрудников, которых он принял на работу. Это заявление не оставляло места обвинениям в сексуальном домогательстве, однако как-то один из старших криптографов по глупости решил проверить справедливость слов шефа. Однажды, в первый год своей работы в агентстве, Сьюзан заглянула в комнату новых криптографов за какими-то бумагами. Уже направляясь к двери, она увидела свое фото на доске объявлений и едва не лишилась чувств. На фотографии она была изображена наклонившейся над постелью, в одних трусиках. Как выяснилось, кто-то из криптографов сосканировал фотографию из порножурнала и приставил к телу головы модели голову Сьюзан. Получилось очень даже правдоподобно.

Рядом с ним кого-то рвало. Хорошенькая картинка. Беккер застонал и начал выбираться из расписанного краской из баллончиков зала. Он оказался в узком, увешанном зеркалами туннеле, который вел на открытую террасу, уставленную столами и стульями. На террасе тоже было полно панков, но Беккеру она показалась чем-то вроде Шангри-Ла: ночное летнее небо над головой, тихие волны долетающей из зала музыки.

Больше никаких мотоциклов, пообещал он. Ярко освещенное помещение аэровокзала сияло стерильной чистотой. Здесь не было ни души, если не считать уборщицы, драившей пол.

 - Коммандер. Внезапно Сьюзан вспомнила, что он должен быть в лаборатории систем безопасности. Она кружила по пустому кабинету, все еще не преодолев ужас, который вызвало у нее общение с Хейлом. Надо выбираться из шифровалки.

 - Я, конечно, предположил, что это не та Северная Дакота, которую мы ищем, но на всякий случай проверил эту запись. Представь себе мое изумление, когда я обнаружил множество сообщений Энсея Танкадо.  - Стратмор приподнял брови.

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