UNIT 26 Fundamentals of HVAC

(heating, ventilating and air conditioning)

Read, translate the following text and be ready to fulfil the tests:

HVAC (heating, ventilating and air conditioning) is the technology of indoor and vehicular environmental comfort. Its goal is to provide thermal comfort and acceptable indoor air quality. Heating, ventilating and air conditioning is based on inventions and discoveries made by Nikolay Lvov, Michael Faraday, Willis Carrier, Reuben Trane, James Joule, William Rankine, Sadi Carnot and many others. The invention of the components of HVAC systems went hand-in-hand with the industrial revolution, and new methods of modernization, higher efficiency and system control are constantly being introduced by companies and inventors worldwide.

HVAC system design is a subdiscipline of mechanical engineering, based on the principles of thermodynamics, fluid mechanics, and heat transfer. Refrigeration is sometimes added to the field's abbreviation as HVAC&R or HVACR, or ventilating is dropped as in HACR. HVAC is important in the design of medium to large industrial and office buildings such as skyscrapers and in marine environments such as aquariums, where safe and healthy building conditions are regulated with respect to temperature and humidity, using fresh air from outdoors.

Ventilating is the process of "changing" or replacing air in any space to provide high indoor air quality (i.e. to control temperature, replenish oxygen, or remove moisture, odors, smoke, heat, dust, airborne bacteria, and carbon dioxide). Ventilation is used to remove unpleasant smells and excessive moisture, introduce outside air, to keep interior building air circulating, and to prevent stagnation of the interior air. Ventilation includes both the exchange of air to the outside as well as circulation of air within the building. It is one of the most important factors for maintaining acceptable indoor air quality in buildings. Methods for ventilating a building may be divided into mechanical / forced and natural types.

The three central functions of heating, ventilating, and air-conditioning are interrelated, especially with the need to provide thermal comfort and acceptable indoor air quality within reasonable installation, operation, and maintenance costs. HVAC systems can provide ventilation, reduce air infiltration, and maintain pressure relationships between spaces. The means of air delivery and removal from spaces is known as room air distribution. In modern buildings the design, installation, and control systems of these functions are integrated into one or more HVAC systems. For very small buildings, contractors normally estimate the capacity, engineer, and select HVAC systems and equipment. For larger buildings, building service designers, mechanical engineers, or building services engineers analyze, design, and specify the HVAC systems. Specialty mechanical contractors then fabricate and commission the systems.

Although HVAC is executed in individual buildings or other enclosed spaces, the equipment involved is in some cases an extension of a larger district heating or district cooling network, or a combined DHCnetwork. In such cases, the operating and maintenance aspects are simplified and metering becomes necessary to bill for the energy that is consumed, and in some cases energy that is returned to the larger system. For example, at a given time one building may be utilizing chilled water for air conditioning and the warm water it returns may be used in another building for heating, or for the overall heating-portion of the DHC network. Basing HVAC on a larger network helps to provide an economy of scale that is often not possible for individual buildings, for utilizing renewable energy sources such as solar heat, winter's cold, the cooling potential in some places of lakes or seawater for free cooling.

Read and memorize the active vocabulary to the text:

Active Vocabulary

1. indoor внутри помещения

2. vehicular относящийся к средствам передвижения

3. environmental относящийся к окружающей обстановке, среде

4. acceptable приемлемый; пригодный, допустимый

5. invention открытие, изобретение

6. with respect to по отношению к

7. humidity влажность, сырость

8. to replace заменять, замещать

9. to replenish обновлять, освежать

10. airborne распространяющийся в воздухе

11. excessive чрезмерный; излишний; избыточный

12. to maintain обслуживать; содержать в хорошем состоянии

13. to interrelate взаимосвязывать; находиться во взаимосвязи

14. reasonable рациональный, приемлемый, допустимый

15. delivery доставка; поставка; снабжение

16. removal удаление; устранение

17. to estimate оценивать, подсчитывать; составлять смету

18. to specify идентифицировать, характеризовать конкретизировать

19. specialty специальность; особенность, отличительная черта

20. to execute исполнять, выполнять, осуществлять

21. DHC network district heating or district cooling network

22. renewable воспроизводимый, возобновляемый

CONTROL TESTS

TEST I

Decide whether these statements are true or false:

1. a). Ventilating is the process of generating heat (warmth) for the building.

b). Ventilating is the process of removing any remaining particles before the air is recirculated again.

c). Ventilating is the process of "changing" or replacing air in any space to provide high indoor air quality.

2. a). The invention of the components of HVAC systems went hand-in-hand with the goal to provide thermal comfort and acceptable indoor air quality.

b). The invention of the components of HVAC systems went hand-in-hand with the industrial revolution.

c). The invention of the components of HVAC systems went hand-in-hand with the development of means of air delivery and removal from spaces.

3. a). HVAC system design is the technology of indoor and vehicular environmental comfort.

b). HVAC system design is a ductwork system of supply and return air through metal or fiberglass ducts.

c). HVAC system design is a subdiscipline of mechanical engineering.

4. a). Ventilation is used to remove unpleasant smells and excessive moisture, introduce outside air.

b). Ventilation is used to transport the heat to the rooms.

c). Ventilation is used to remove dust and pollen particles.

5. a). Methods for ventilating a building may be divided into application of the distribution systems and gravity-fed systems.

b). Methods for ventilating a building may be divided into mechanical / forced and natural types.

c). Methods for ventilating a building may be divided into radiation, convection, or conduction types.

TEST II

Match words in columns A and B (synonym match):

A B

1. heating a). vaulting b). development

c). broadcasting d). warming

2. acceptable a). tensile b). admissible

c). innovative d). high-pitch

3. goal a). aim b). truss

c). grid d). shell

4. efficiency a). availability b). possibility

c). productivity d). workability

5. medium a). concern b). environment

c). bend d). mould

6. safe a). strong b). convenient

c). excelent d). secure

7. maintenance a). mortar b). service

c). density d). aggregate

8. indoor a). external b). capable

c). internal d). brittle

9. circulation a). propagation b). displacement

c). expansion d). fulfillment

10. estimate a). phenomena b). reaction

c). trend d). evaluation

TEST III

Select the best possible answer out of the choices from the list to the statements (multiple choice):

1.HVAC is important in the design of …

a. replacing air in any space to provide high indoor air quality.

b. removing dust, airborne bacteria, and carbon dioxide.

c. medium to large industrial and office buildings.

2. The three central functions of HVAC …

a. are interrelated, especially with the need to provide thermal comfort and acceptable indoor air quality.

b. can use very little energy, but care must be taken to ensure comfort.

c. can often be controlled via dilution or replacement with outside air.

3. HVAC systems can provide …

a. reduction of carbon monoxide exposure.

b. filtration through air cleaners to remove dust and pollen particles.

c. ventilation, reduce air infiltration, and maintain pressure relationships between spaces.

4. Ventilation includes both …

a. cooling and humidity control for all or part of a building.

b. the exchange of air to the outside as well as circulation of air within the building.

c. heated water or steam.

5. Ventilation is used …

a. for maintaining thermal comfort solely via natural ventilation.

b. to introduce and distribute cool outdoor air.

c. to prevent stagnation of the interior air.

TEST IV