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HVAC
Heating, ventilation, and air conditioning (HVAC ) is the use of various technologies to control the temperature, humidity, and purity of the air in an enclosed space. Its goal is to provide thermal comfort and acceptable indoor air quality. 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 "ventilation" is dropped, as in HACR (as in the designation of HACR-rated circuit breakers). HVAC is an important part of residential structures such as single family homes, apartment buildings, hotels, and senior living facilities; medium to large industrial and office buildings such as skyscrapers and hospitals; vehicles such as cars, trains, airplanes, ships and submarines; and in marine environments, where safe and healthy building conditions are regulated with respect to temperature and humidity, using fres ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HVAC Control System
HVAC (Heating, Ventilation and Air Conditioning) equipment needs a control system to regulate the operation of a heating and/or air conditioning system. Usually a sensing device is used to compare the actual state (e.g. temperature) with a target state. Then the control system draws a conclusion what action has to be taken (e.g. start the blower). Direct digital control Central controllers and most terminal unit controllers are programmable, meaning the direct digital control program code may be customized for the intended use. The program features include time schedules, set points, controllers, logic, timers, trend logs, and alarms. The unit controllers typically have analog and digital inputs that allow measurement of the variable (temperature, humidity, or pressure) and analog and digital outputs for control of the transport medium (hot/cold water and/or steam). Digital inputs are typically (dry) contacts from a control device, and analog inputs are typically a voltage or cur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sick Building Syndrome
Sick building syndrome (SBS) is a condition in which people develop symptoms of illness or become infected with chronic disease from the building in which they work or reside. In scientific literature, SBS is also known as building-related illness (BRI), building-related symptoms (BRS), or idiopathic environmental intolerance (IEI). The main identifying observation is an increased incidence of complaints of such symptoms as headache, eye, nose, and throat irritation, fatigue, dizziness, and nausea. The 1989 Oxford English Dictionary defines SBS in that way. The World Health Organization created a 484-page tome on indoor air quality in 1984, when SBS was attributed only to non-organic causes, and suggested that the book might form a basis for legislation or litigation. The outbreaks may or may not be a direct result of inadequate or inappropriate cleaning. SBS has also been used to describe staff concerns in post-war buildings with faulty building aerodynamics, construction m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ASHRAE
The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE ) is an American professional association seeking to advance heating, ventilation, air conditioning and refrigeration (HVAC&R) systems design and construction. ASHRAE has over 50,000 members in more than 130 countries worldwide. ASHRAE's members comprise building services engineers, architects, mechanical contractors, building owners, equipment manufacturers' employees, and others concerned with the design and construction of HVAC&R systems in buildings. The society funds research projects, offers continuing education programs, and develops and publishes technical standards to improve building services engineering, energy efficiency, indoor air quality, and sustainable development. History ASHRAE was founded in 1894 at a meeting of engineers in New York City, formerly headquartered at 345 East 47th Street (the United Engineering Center), and has held an annual meeting since 1895. Until ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermal Comfort
Thermal comfort is the condition of mind that expresses subjective satisfaction with the thermal environment.ANSI/ASHRAE Standard 55-2017, Thermal Environmental Conditions for Human Occupancy The human body can be viewed as a heat engine where food is the input energy. The human body will release excess heat into the environment, so the body can continue to operate. The heat transfer is proportional to temperature difference. In cold environments, the body loses more heat to the environment and in hot environments the body does not release enough heat. Both the hot and cold scenarios lead to discomfort. Maintaining this standard of thermal comfort for occupants of buildings or other enclosures is one of the important goals of HVAC ( heating, ventilation, and air conditioning) design engineers. Thermal neutrality is maintained when the heat generated by human metabolism is allowed to dissipate, thus maintaining thermal equilibrium with the surroundings. The main factors that in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Indoor Air Quality
Indoor air quality (IAQ) is the air quality within buildings and Nonbuilding structure, structures. Poor indoor air quality due to indoor air pollution is known to affect the health, comfort, and well-being of building occupants. It has also been linked to Sick Building Syndrome, sick building syndrome, respiratory issues, reduced productivity, and impaired learning in schools. Common pollutants of indoor air include: Passive smoking, secondhand tobacco smoke, Household air pollution, air pollutants from indoor combustion, radon, Mold health issues, molds and other allergens, carbon monoxide, volatile organic compounds, legionella and other bacteria, Asbestos, asbestos fibers, carbon dioxide, ozone and Atmospheric particulate matter, particulates. Source control, filtration, and the use of ventilation (architecture), ventilation to dilute contaminants are the primary methods for improving indoor air quality. Although ventilation is an integral component of maintaining good indoo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ASHRAE Handbook
The ASHRAE Handbook is the four-volume flagship publication of the nonprofit technical organization ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers). This Handbook is considered the most comprehensive and authoritative repository of practical knowledge on the various topics that form the field of heating, ventilation, air-conditioning, and refrigeration ( HVAC&R). The four volumes are ''Fundamentals'', ''Refrigeration'', ''HVAC Applications'' ("Applications"), and ''HVAC Systems and Equipment'' ("Systems and Equipment"). Members of ASHRAE receive the current volume, in both print and CD-ROM form, each year as a basic membership benefit. An enhanced electronic version, known as ''ASHRAE Handbook Online'' is a web-based version updated annually that contains the four latest volumes as well as extra content such as calculations, demonstration videos, and spreadsheets. The various versions of the Handbook are typically available to the public v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ventilation (architecture)
Ventilation is the intentional introduction of outdoor air into a space. Ventilation is mainly used to control indoor air quality by diluting and displacing indoor effluents and pollutants. It can also be used to control indoor temperature, humidity, and air motion to benefit thermal comfort, satisfaction with other aspects of the indoor environment, or other objectives. The intentional introduction of outdoor air is usually categorized as either mechanical ventilation, natural ventilation, or mixed-mode ventilation. * Mechanical ventilation is the intentional fan-driven flow of outdoor air into and/or out from a building. Mechanical ventilation systems may include supply fans (which push outdoor air into a building), Exhaust ventilation systems, exhaust fans (which draw air out of a building and thereby cause equal ventilation flow into a building), or a combination of both (called balanced ventilation if it neither pressurizes nor depressurizes the inside air, or only slightly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mechanical Engineering
Mechanical engineering is the study of physical machines and mechanism (engineering), mechanisms that may involve force and movement. It is an engineering branch that combines engineering physics and engineering mathematics, mathematics principles with materials science, to design, analyze, manufacture, and maintain mechanical systems. It is one of the oldest and broadest of the List of engineering branches, engineering branches. Mechanical engineering requires an understanding of core areas including mechanics, Analytical dynamics, dynamics, thermodynamics, materials science, design, structural analysis, and electricity. In addition to these core principles, mechanical engineers use tools such as computer-aided design (CAD), computer-aided manufacturing (CAM), computer-aided engineering (CAE), and product lifecycle management to design and analyze manufacturing plants, industrial equipment and industrial machinery, machinery, HVAC, heating and cooling systems, transport systems, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Refrigeration
Refrigeration is any of various types of cooling of a space, substance, or system to lower and/or maintain its temperature below the ambient one (while the removed heat is ejected to a place of higher temperature).IIR International Dictionary of Refrigeration, http://dictionary.iifiir.org/search.php ASHRAE Terminology, https://www.ashrae.org/technical-resources/free-resources/ashrae-terminology Refrigeration is an artificial, or human-made, cooling method. Refrigeration refers to the process by which energy, in the form of heat, is removed from a low-temperature medium and transferred to a high-temperature medium. This work of energy transfer is traditionally driven by work (physics), mechanical means (whether ice or electromechanics, electromechanical machines), but it can also be driven by heat, magnetism, electricity, laser cooling, laser, or other means. Refrigeration has many applications, including household refrigerators, industrial freezers, cryogenics, and air conditioni ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Building Engineering
Architectural engineering or architecture engineering, also known as building engineering, is a Academic discipline, discipline that deals with the engineering and construction of buildings, such as environmental, structural, mechanical, electrical, computational, embeddable, and other research domains. It is related to Architecture, Mechatronics Engineering, Computer engineering, Computer Engineering, Aerospace engineering, Aerospace Engineering, and civil engineering, Civil Engineering, but distinguished from Interior design, Interior Design and architectural design, Architectural Design as an art and science of designing infrastructure through these various engineering disciplines, from which properly align with many related surrounding engineering advancements. From reduction of greenhouse gas emissions to the construction of resilient buildings, architectural engineers are at the forefront of addressing several major challenges of the 21st century. They apply the latest scie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Free Cooling
Free cooling is an economical method of using low external air temperatures to assist in chilling water, which can then be used for industrial processes, or air conditioning systems. The chilled water can either be used immediately or be stored for the short- or long-term. When outdoor temperatures are lower relative to indoor temperatures, this system utilizes the cool outdoor air as a free cooling source. In this manner, the system replaces the chiller in traditional air conditioning systems while achieving the same cooling result. Such systems can be made for single buildings or district cooling networks. Operation For a human-powered version, see yakhchal. When the ambient air temperature drops to a set temperature, a modulating valve allows all or part of the chilled water to by-pass an existing chiller and run through the free cooling system, which uses less power and uses the lower ambient air temperature to cool the water in the system. This can be achieved by installing ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
