|
Subcooling
The term subcooling (also called undercooling) refers to the intentional process of cooling a liquid below its normal boiling point. For example, water boils at 373 K; at room temperature (293 K) liquid water is termed "subcooled". Subcooling is a common stage in refrigeration cycles and steam turbine cycles. Some rocket engines use subcooled propellants. In refrigeration systems, subcooling the refrigerant is necessary to ensure the completion of the remaining stages of the refrigeration cycle. The subcooling stage provides certainty that the refrigerant is fully liquid before it reaches the next step on the cycle, the thermal expansion valve, where the presence of gas can be disruptive.Ibrahim Dinçer, Refrigeration Systems and Applications. John Wiley & Sons, Second Edition, 2010, pp. 169-170/ref> Subcooling is often accomplished in heat exchangers. Subcooling and superheating, which are similar and inverse processes, are both important for the stability and well ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Economizer
Economizers (US and Oxford spelling), or economisers (UK), are mechanical devices intended to reduce energy consumption, or to perform useful function such as preheating a fluid. The term economizer is used for other purposes as well. Boiler, power plant, heating, refrigeration, ventilating, and air conditioning (HVAC) may all use economizers. In simple terms, an economizer is a heat exchanger. Stirling engine Robert Stirling's innovative contribution to the design of hot air engines of 1816 was what he called the 'Economiser'. Later known as the regenerator, it stored heat from the hot portion of the engine as the air passed to the cold side, and released heat to the cooled air as it returned to the hot side. This innovation improved the efficiency of the Stirling engine enough to make it commercially successful in particular applications, and has since been a component of every air engine that is called a Stirling engine. Boilers In boilers, economizers are heat exchange de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flash-gas
In refrigeration, flash-gas is refrigerant in gas form produced spontaneously when the condensed liquid is subjected to boiling. The presence of flash-gas in the liquid lines reduces the efficiency of the refrigeration cycle.Refrigeration and Air Conditioning Technology, William Whitman. 2005 New York, Page 37. . It can also lead several expansion systems to work improperly, and increase superheating at the evaporator. This is normally perceived as an unwanted condition caused by dissociation between the volume of the system, and the pressures and temperatures that allow the refrigerant to be liquid. Flash-gas must not be confused with lack of condensation, but special gear such as receivers, internal heat exchangers, insulation, and refrigeration cycle optimizers may improve condensation and avoid gas in the liquid lines. Common Causes Heat absorption and pressure loss The most common causes driving the fluid to change its phase when in the liquid line are excessive length of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boiling Point
The boiling point of a substance is the temperature at which the vapor pressure of a liquid equals the pressure surrounding the liquid and the liquid changes into a vapor. The boiling point of a liquid varies depending upon the surrounding environmental pressure. A liquid in a partial vacuum, i.e., under a lower pressure, has a lower boiling point than when that liquid is at atmospheric pressure. Because of this, water boils at 100°C (or with scientific precision: ) under standard pressure at sea level, but at at altitude. For a given pressure, different liquids will boiling, boil at different temperatures. The normal boiling point (also called the atmospheric boiling point or the atmospheric pressure boiling point) of a liquid is the special case in which the vapor pressure of the liquid equals the defined atmospheric pressure at sea level, one Atmosphere (unit), atmosphere. At that temperature, the vapor pressure of the liquid becomes sufficient to overcome atmospheric pre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Superheating
In thermodynamics, superheating (sometimes referred to as boiling retardation, or boiling delay) is the phenomenon in which a liquid is heated to a temperature higher than its boiling point, without boiling. This is a so-called ''metastable state'' or '' metastate'', where boiling might occur at any time, induced by external or internal effects.Debenedetti, P.G.Metastable Liquids: Concepts and Principles; Princeton University Press: Princeton, NJ, USA, 1996.Maris, H., Balibar, S. (2000"Negative Pressures and Cavitation in Liquid Helium"Physics Today 53, 29 Superheating is achieved by heating a homogeneous substance in a clean container, free of nucleation sites, while taking care not to disturb the liquid. This may occur by microwaving water in a very smooth container. Disturbing the water may cause an unsafe eruption of hot water and result in burns. Cause Water is said to "boil" when bubbles of water vapor grow without bound, bursting at the surface. For a vapor bubble ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SpaceX Starship
Starship is a two-stage fully reusable launch vehicle, reusable super heavy-lift launch vehicle under development by American aerospace company SpaceX. On 20 April 2023, with the Starship flight test 1, first Integrated Flight Test, Starship became the most massive and most powerful vehicle ever to fly. SpaceX has developed Starship with the intention of lowering launch costs using economies of scale. SpaceX aims to achieve this by Fully reusable orbital launch vehicle, reusing both rocket stages by catching them with the launch and integration tower, increasing payload mass to orbit, increasing launch frequency, Mass production, mass-manufacturing the rockets and General-purpose technology, adapting it to a wide range of space missions. Starship is the latest project in SpaceX's SpaceX reusable launch system development program, reusable launch system development program and SpaceX Mars colonization program, plan to colonize Mars. Starship's two stages are the SpaceX Super Hea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Efficient Energy Use
Efficient energy use, or energy efficiency, is the process of reducing the amount of energy required to provide products and services. There are many technologies and methods available that are more energy efficient than conventional systems. For example, building insulation, insulating a building allows it to use less heating and cooling energy while still maintaining a Thermal comfort, comfortable temperature. Another method made by Lev Levich is to remove energy subsidies that promote high energy consumption and inefficient energy use. Improved energy efficiency in Green building, buildings, industrial processes and Energy efficiency in transport, transportation could reduce the world's energy needs in 2050 by one third. There are two main motivations to improve energy efficiency. Firstly, one motivation is to achieve Operating cost, cost savings during the operation of the appliance or process. However, installing an energy-efficient technology comes with an upfront cost, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Temperature
Temperature is a physical quantity that quantitatively expresses the attribute of hotness or coldness. Temperature is measurement, measured with a thermometer. It reflects the average kinetic energy of the vibrating and colliding atoms making up a substance. Thermometers are calibrated in various temperature scales that historically have relied on various reference points and thermometric substances for definition. The most common scales are the Celsius scale with the unit symbol °C (formerly called ''centigrade''), the Fahrenheit scale (°F), and the Kelvin scale (K), with the third being used predominantly for scientific purposes. The kelvin is one of the seven base units in the International System of Units (SI). Absolute zero, i.e., zero kelvin or −273.15 °C, is the lowest point in the thermodynamic temperature scale. Experimentally, it can be approached very closely but not actually reached, as recognized in the third law of thermodynamics. It would be impossible ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Launch Vehicle
A launch vehicle is typically a rocket-powered vehicle designed to carry a payload (a crewed spacecraft or satellites) from Earth's surface or lower atmosphere to outer space. The most common form is the ballistic missile-shaped multistage rocket, but the term is more general and also encompasses vehicles like the Space Shuttle. Most launch vehicles operate from a launch pad, supported by a missile launch control center, launch control center and systems such as vehicle assembly and fueling. Launch vehicles are engineered with advanced aerodynamics and technologies, which contribute to high operating costs. An orbital spaceflight, orbital launch vehicle must lift its payload at least to the boundary of space, approximately and accelerate it to a horizontal velocity of at least . Suborbital spaceflight, Suborbital vehicles launch their payloads to lower velocity or are launched at elevation angles greater than horizontal. Practical orbital launch vehicles use chemical prope ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Falcon 9
Falcon 9 is a Reusable launch system#Partial reusable launch systems, partially reusable, two-stage-to-orbit, medium-lift launch vehicle designed and manufactured in the United States by SpaceX. The first Falcon 9 launch was on June 4, 2010, and the first commercial resupply mission to the International Space Station (ISS) launched on October 8, 2012. In 2020, it became the first commercial rocket to launch humans to orbit. The Falcon 9 has been noted for its reliability and high launch cadence, with successful launches, two in-flight failures, one partial failure and one pre-flight destruction. It is the most-launched American orbital rocket in history. The rocket has two-stage-to-orbit, two stages. The first (booster) stage carries the second stage and payload to a predetermined speed and altitude, after which the second stage accelerates the payload to its target orbit. The Booster (rocketry), booster is capable of Vertical takeoff, vertical landing, landing vertically to fa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SpaceX
Space Exploration Technologies Corp., commonly referred to as SpaceX, is an America, American space technology company headquartered at the SpaceX Starbase, Starbase development site in Starbase, Texas. Since its founding in 2002, the company has made numerous advancements in rocket propulsion, reusable launch vehicles, human spaceflight and satellite constellation technology. , SpaceX is the world's dominant space launch provider, its launch cadence eclipsing all others, including private competitors and national programs like the Chinese space program. SpaceX, NASA, and the United States Armed Forces work closely together by means of Government contractor, governmental contracts. SpaceX was founded by Elon Musk in 2002 with a vision of decreasing the costs of space launches, paving the way to SpaceX ambition of colonizing Mars, a sustainable colony on Mars. In 2008, Falcon 1 successfully launched into orbit after three failed launch attempts. The company then pivoted towar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rocket Propellant
Rocket propellant is used as reaction mass ejected from a rocket engine to produce thrust. The energy required can either come from the propellants themselves, as with a chemical rocket, or from an external source, as with ion engines. Overview Rockets create thrust by expelling mass rear-ward, at high velocity. The thrust produced can be calculated by multiplying the mass flow rate of the propellants by their exhaust velocity relative to the rocket (specific impulse). A rocket can be thought of as being accelerated by the pressure of the combusting gases against the combustion chamber and nozzle, not by "pushing" against the air behind or below it. Rocket engines perform best in outer space because of the lack of air pressure on the outside of the engine. In space it is also possible to fit a longer nozzle without suffering from flow separation. Most chemical propellants release energy through redox chemistry, more specifically combustion. As such, both an oxidizing agen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
