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A condenser is an apparatus or item of equipment used to condense (change the physical state of) a substance from its gaseous to its liquid state. In the laboratory, condensers are generally used in procedures done with organic liquids brought into gaseous state through heating with or without lowering the pressure (applying vacuum)—though applications in inorganic and other chemistry areas exist. While condensers can be applied at various scales, in the research, training, or discovery laboratory, one most often uses glassware designed to pass a vapor flow over an adjacent cooled chamber. In simplest form, such a condenser consists of a single glass tube with outside air providing cooling. A further simple form, the Liebig-type of condenser, involves concentric glass tubes, an inner one through which the hot gases pass, and an outer, "ported" chamber through which a cooling fluid passes, to reduce the gas temperature in the inner, to afford the condensation. Depending on the application (chemical components being separated, and the required operating temperature) and the scale of the process (from very few microliters to process scales involving many liters), different types of condensers and means of cooling are used. Alongside the temperature differential and heat capacities of the cooling fluids (e.g., air, water, aqueous-organic co-solvents), the size of the cooling surface and the way in which gas (vapor) and condensing liquid states come into contact are critical in the choice or design of a condenser system. Since at least the 19th century, scientists have sought creative designs to maximize the surface area of vapor-liquid contact and heat exchange. Many types of laboratory condensers—simpler Liebig and Allihn, coiled Graham types, simple and Dimroth types of cold finger condensers, etc.—now common, have evolved to meet the practical need of larger cooling surfaces and controlled boiling and condensation in various procedures involving distillation, and a further very wide array of materials for "packing" simpler condensers to increase surface area (e.g., plass, ceramic, and metal beads, rings, wool, etc.) have been studied and applied. Likewise, the configurations of laboratory apparatus involving condensers are many and varied, to cover low and high boiling solvents, simple and complex separations, etc. Several common process types based on the change of physical state provided by condensers can easily be described, including ''simple evaporations'' or "solvent stripping" (the bulk removal of all volatiles to leave behind concentrated solutes present in the original solution being evaporated), ''reflux operations'' (where the aim is to contain all volatiles while providing a constant process temperature established by the boiling point of the solvent system being used), and ''separation/distillation operations'' (where high theoretical plates provide for selective delivery of one or more volatile components of a complex "mixture" in a controlled fashion). The direction of vapor and condensate flows in the laboratory condenser chosen for each of these may vary (e.g., being ''countercurrent'' in reflux procedures, and ''concurrent'' in many simple distillation procedures), as do the optimal flow direction for the cooling fluid, etc. In all processes, condenser selection/design requires that the heat of entering vapor never overwhelm the condenser and cooling mechanism; as well, the thermal gradients and material flows established during the gas-liquid transition are critical aspects, so that as processes increase in scale from laboratory to pilot plant and beyond, the design of condenser systems becomes a precise engineering science. == Operation == A condenser is a piece of apparatus or equipment that can be used to condense, that is, to change the physical state of a substance from its gaseous to its liquid state; in the laboratory, it is generally used in procedures done with organic liquids brought into gaseous state through heating or application of vacuum (lowered pressure), though processes often involve at least trace amounts of the common inorganic component water, and can involve other inorganic substances as well. Condensers can be applied at various scales, from micro-scale (very few microliters) to process-scale (many liters), using laboratory glassware and occasionally metalware that accomplishes the cooling of the vapor generated by boiling (through heating or application of vacuum). In simplest form, a condenser can consist of a single tube of glass or metal, where the flow of outside air produces the cooling. In a further simple form, condensers consist of concentric glass tubes, with the tube through which the hot gases begin to pass running the length of the apparatus. The second tube defines an outer chamber through which air, water, or other cooling fluids can pass to reduce the temperature of the gasses to afford the condensation; hence, the outer tube (or, as designs become more complex, outer cooling chamber) has an inlet and an outlet to allow the cooling fluid to enter and exit. The specific requirement that components in the solution being "fractionated" (divided into component fractions) have differing boiling points, and the varying demands of heat exchange for the various chemical processes using condensers have led to design of very wide varieties of types, with a general design theme being creative ways in which: * first, the surface area for vapor-liquid interaction and heat exchange can be increased (which leads to an increased number of theoretical plates, a metric related to an apparatus's efficiency in separating components with smaller differences in boiling point), and * second, ways in which to control common difficulties experienced in real distillations (such as "flooding and channeling", see below).〔 The combination of these has taken the simple condenser concept through simple changes (e.g., addition, in Allihn-type condensers, of "bubbles" or undulations to the inner, straight vapor tube of the simple ''Liebig'' design, so that diethyl ether (b.p., ca. 35°C), could be accommodated), on to many unique condenser configurations, types of "packings" of the vapor space, and applied cooling media and mechanisms (see below). In this array of designs, the direction of vapor and condensate flows depends on the specific application (e.g., being ''countercurrent'' in reflux procedures, and concurrent in many simpler distillation procedures); the same is true with regard to the optimal flow direction for the cooling fluid (air, water, aqueous ethylene glycol co-solutions, etc.) relative to the direction of vapor flow. Note, while the traditional coolants, air and chilled tap water, have often been used without recirculation (i.e., allowed to exit to atmosphere or drain, respectively), larger scale operations and municipal and other regulations make engineered recirculation necessary, and it is always required for special cooling liquids, such as low temperature alcohols and co-solutions. Designing and maintaining systems and processes using condensers requires that the heat of the entering vapor never overwhelm the ability of the chosen condenser and cooling mechanism; as well, the thermal gradients and material flows established are critical aspects, and as processes scale from laboratory to pilot plant and beyond, the design of condenser systems becomes a precise engineering science.〔 Use of condensers in chemical procedures—when not performed at fixed, lowered pressure by careful vacuum control—inevitably involves transiently fluctuating pressures within the apparatus, so that isolating the apparatus while allowing it to be an open rather than sealed system becomes a practical issue; this is particularly true, when chemical reactions are performed that are air- or moisture-sensitive. If the reaction or process using condensers cannot be left open to atmosphere, its isolation is accomplished in simplest fashion via drying tubes (an attached tube packed with desiccant) or other specially packed scavenging tubes, that allows gasses to pass, and so pressure equalization, but prevents entry of substances deleterious to the ongoing chemistry; alternatively, the apparatus can be vented through a "bubbler" that prevents entry of laboratory atmosphere either by allowing the internal volume to push and pull against a volume of resisting liquid (e.g., mineral or silicone oil), or by keeping a positive pressure of inert, "blanketing" gas (e.g., nitrogen or argon) that vents through a similar volume of liquid. Attachment of such during tubes and bubblers can be direct, or indirect via gas/vacuum lines and manifolds. Practically, in modern milliliter to liter-scale laboratory operations involving condensers, pieces of apparatus are often held together tightly by complementary, tapered "inner" and "outer" "joints" ground to produce very tight fits (augmented as necessary by PTFE rings or sleeves, or uniquely formulated greases or waxes; increasingly, other means of joint glass, such as threaded fittings with adapters, are used (some of which are also used across the range of process scales). 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Condenser (laboratory)」の詳細全文を読む スポンサード リンク
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