BU2

• Thermal convection


  The transfer of thermal energy by actual physical movement from one location to another of a substance in which thermal energy is stored. Heat convection is often the primary mode of energy transfer in liquids and gases. A familiar example of convection is the boiling of water in a pot
• HVAC


  Heating, Ventilation and Air Conditioning. Refers to the different systems used for moving air between indoor and outdoor areas, along with heating and cooling both residential and commercial buildings. They are the systems that keep you warm and cozy in the winter and feeling cool and fresh in the summer. They also are the systems that filter and clean indoor air to keep you healthy and maintain humidity levels at optimal comfort levels.
• Theory of heat


  The caloric theory is an obsolete scientific theory that heat consists of a self-repellent fluid called caloric that flows from hotter bodies to colder bodies
• Air conditioning system


  Is an electrical device that is purposely installed for the removal of heat and moisture from the interior of an occupied space
• Heat conduction


  Also called diffusion, is the direct microscopic exchange of kinetic energy of particles through the boundary between two systems. When an object is at a different temperature from another body or its surroundings, heat flows so that the body and the surroundings reach the same temperature, at which point they are in thermal equilibrium. Such spontaneous heat transfer always occurs from a region of high temperature to another region of lower temperature, as described in the second law of thermodynamics
• Subterranean


  Most AC system stores and rejects heat in pipes called?
• Window AC


  These used to be a very common choice for controlling the temperature in a small room
• Portable AC


  Are relatively easy to move, but not as much as their name implies
• Ducted AC


  Also known as central air conditioning, can be the most efficient in many situations. This system involves a large compressor on the outside of the building, an internal evaporative unit and ducts that bring conditioned air to various rooms through vents. This system will require some significant modifications to your home and tends to have a high upfront cost
• AC for diverse range of situations


  While ducted air conditioning may be the most efficient choice overall, it wouldn't be suitable for someone who just wants to cool down or warm up a single room
• Evaporator coil


  Lined with thin aluminum fins, the evaporator coil looks and functions almost like a car's radiator except that it absorbs heat instead of rejecting it. As cold refrigerant enters the evaporator coil, it also draws latent heat from the air passing through the coil. The capture of this heat energy transforms the refrigerant from a cold mist to a warm vapor. Meanwhile, the air that passes through the evaporator coil loses its warmth and moisture, resulting in the cool, dry air that's fed throughout your home via the ductwork. Evaporator coils are mostly shielded from dust and debris thanks to the HVAC air filter
• Compressor


  Takes in the warm refrigerant vapor and compresses it into a denser form. This process also causes an increase in temperature and pressure, making the refrigerant hotter than before. The pressurized refrigerant is eventually pushed through the condenser coil
• Condenser coil


  It's job is to release heat from the refrigerant. Think of your car's radiator and how it's designed to help dissipate heat from the coolant circulating inside. In fact, the way the condenser coil operates is pretty similar to how the evaporator coil works. A condenser fan built into the outdoor cabinet directs ambient air through the condenser coil — similar to how the indoor air handler's built-in fan directs air through the condenser coil. But instead of absorbing latent heat, the condenser coil uses the air flow to expel heat from the refrigerant. This process changes the refrigerant from hot, high-pressure vapor into a hot liquid. Before the refrigerant can be reused in the refrigerant cycle, there's one more important component it must go through
• Expansion valve


  In order to complete the air conditioning process, the refrigerant needs to be transformed back into a cold mist. It essentially converts the flow of liquid refrigerant back into vapor form. The liquid refrigerant enters the valve through an extremely narrow orifice designed to meter the amount of refrigerant that passes through. A temperature-sensing bulb helps modulate the refrigerant flow based on temperatures within the suction line
• Radiant heating system


  In this system, heated fluid is distributed from a warm-water source (e.g. geothermal system, boiler) through plastic tubing that is embedded in the floors, walls, or ceilings of a space
• Radiant cooling system


  Typically designed in conjunction with radiant heating, this system can circulate chilled fluid through the same network of embedded plastic tubing. This network of tubes can turn floors, walls, and ceilings into cooled surfaces that evenly absorb sensible* heat energy, including radiant energy from solar gain, people, lights, computers, etc., in addition to some convective heat transfer from the air
• Sensible heat


  Heat that causes a change in temperature in an object
• Hydronic radiant heating


  Heating makes use of hot water tubes that run below the home's floors
• Electric radiant heating


  Typically consist of electric heating cables
• Ceiling


  The most ideal surface for radiant systems due to its unobstructed, invisible, and highly efficient heating and cooling capabilities
• Hydronic system


  Are heating systems that circulate water through pipes to either heat or cool a building
• Solid mats


  Are often the most expensive electric system, but they're also the easiest to install. The cable is completely enclosed in synthetic fabric, plastic sheeting or metal foil. The big advantage is that you don't have to embed it as you do loose cable or mesh mats
• Under-mat


  With under tile versions, you simply smooth the mat onto a bed of thin-set (photo above). Then you spread more thin-set with a grout float over the mat. And after it hardens comb more thin-set over the mat to set ceramic or stone tile as you normally would
• Under floating floor mat


  This solid mat system is even easier to install; you just roll out the mats, tape them together and you're done. You can then lay a floating wood or laminate floor directly over the heated flooring
• Under-floor mat technique


  Some mats are sized to fit between joists, so you can heat the floor from below as shown above—a big advantage if you don't want to replace an existing floor. And you can staple mats between joists to heat the floor above
• Heat pump system


  Is basically an all-in-one unit that functions as both the central heat and ac systems in your home. Has a magical reversing valve that switches the system from cooling to heating
• AHU


  Air Handling Unit
• Comfort Air-Conditioning


  Energy of food is converted into chemical energy for functioning of brain, lungs, heart and other organs and this energy is ultimately rejected to the surroundings. Also the internal organs require a temperature close to 35C for their efficient operation, and regulatory mechanisms of human body maintain this temperature by rejecting appropriate amount of heat
• Evaporator


  Is a device used in a process to turn the liquid form of a chemical substance, such as water, into its gaseous form- vapor. The liquid is evaporated, or vaporized, into a gas form of the targeted substance in that process
• Falling film evaporator


  This type of evaporator is generally made of 4-8 m (13-26 ft) tubes enclosed by steam jackets. The uniform distribution of the solution is important when using this type of evaporator. The solution enters and gains velocity as it flows downward. This gain in velocity is attributed to the vapor being evolved against the heating medium, which flows downward as well. This evaporator is usually applied to highly viscous solutions, so it is frequently used in the chemical, sugar, food, and fermentation industries
• Rising film (Long Tube Vertical) evaporator


  In this type of evaporator, boiling takes place inside the tubes, due to heating made (usually by steam) outside the same. Submergence is therefore not desired; the creation of water vapor bubbles inside the tube creates an ascensional flow enhancing the heat transfer coefficient. This type of evaporator is therefore quite efficient, the disadvantage being to be prone to quick scaling of the internal surface of the tubes
• Climbing and falling-film plate evaporator


  Have a relatively large surface area. The plates are usually corrugated and are supported by frame. During evaporation, steam flows through the channels formed by the free spaces between the plates. The steam alternately climbs and falls parallel to the concentrated liquid. The steam follows a co-current, counter-current path in relation to the liquid. The concentrate and the vapor are both fed into the separation stage where the vapor is sent to a condenser. This type of plate evaporator is frequently applied in the dairy and fermentation industries since they have spatial flexibility. A negative point of this type of evaporator is that it is limited in its ability to treat viscous or solid-containing products. There are other types of plate evaporators, which work with only climbing film
• Multiple-effect evaporator


  Unlike single-stage evaporators, these evaporators can be composed of up to seven evaporator stages (effects). The energy consumption for single-effect evaporators is very high and is most of the cost for an evaporation system. Putting together evaporators saves heat and thus requires less energy. Adding one evaporator to the original decreases energy consumption to 50%. Adding another effect reduces it to 33% and so on. A heat-saving-percent equation can be used to estimate how much one will save by adding a certain number of effects
• Agitated thin film evaporator


  Has been very successful with difficult-to-handle products. Simply stated, the method quickly separates the volatile from the less volatile components using indirect heat transfer and mechanical agitation of the flowing product film under controlled conditions. The separation is normally made under vacuum conditions to maximize ∆T while maintaining the most favorable product temperature so that the product only sees equilibrium conditions inside the evaporator and can maximize volatile stripping and recovery
• Condenser


  Its function is to allow high pressure and temperature refrigerant vapor to condense and eject heat. There are three main types: air-cooled, evaporative, and water cooled
• Air-Cooled


  This condenser usually consist of pipes with fins attached, but can occasionally have wires, or even a plate, affixed to the refrigerant's piping. These give the condenser a greater surface area and allow for more efficient cooling. Air circulation is achieved either by static means, where air in contact with the pipes becomes hot and rises to be displaced by cooler air
• Water-Cooled


  This condenser normally consist of an outer tube carrying hot vaporized refrigerant which flows over an inner tube containing a counter flow of cool water. These shell-within-tube condensers are very efficient. Water-cooled condensers are more complex than air-cooled condensers as there are design considerations in water flow regulation and corrosion prevention. However, the advantages of water-cooled systems are that water has a higher exchange coefficient than air so heat transfer will be more efficient
• Evaporative Condenser


  In large systems, this condenser is utilized combining airflow with water. The refrigerant is condensed by using a combination of airflow and water sprayed onto a coil, usually in a tower. The water is then collected in a sump and pumped back to the sprayer. Air is forced up through the tower using forced ventilation
• Compressor


  Is a mechanical device that increases the pressure of a gas by reducing its volume. These are similar to pumps: both increase the pressure on a fluid and both can transport the fluid through a pipe. As gases are compressible, this also reduces the volume of a gas. Liquids are relatively incompressible; while some can be compressed, the main action of a pump is to pressurize and transport liquids
• Reciprocating Air Compressor


  Another popular type of displacement compressor is the reciprocating compressor. These are typically found at smaller work sites such as garages and home construction projects. Unlike the rotary screw compressor, the reciprocating compressor is not designed for continuous use. A reciprocating air compressor has more moving parts than a rotary screw compressor, and these parts are lubricated with oil for smoother movement. These types of air compressors work via a piston inside a cylinder, which compresses and displaces the air to build pressure. Reciprocating compressors can come in single or multi-stage variations, which affects the pressure ranges they can achieve