Heat pipe cell

Our experimental apparatus consists of a sodium containing heat-pipe cell with an active length of 20 cm the buffer gas is argon at a few torr pressure. The sodium density is in the range of 10 -10 cm". The dye laser is Hansch type and is pumped by a 30 kW peak power copper-halide laser with a 25 nsec duration pulse. The dye laser bandwidth is 0.5 cm . The laser beam is spatially filtered and focused into the sodium cell. The laser intensity at the focus is about 10 Mw/cm and is sufficient to form self-trapped filaments. The spectrum of the emission is monitored by 1.2 cm resolution McPearson 0.3m monochromator. The forward emission is photographed by an Alphax B216 camera placed after the sodium cell without any imaging optics. The laser beam is blocked with an on-axis disk. 

The experimental apparatus is discussed elsewhere. Briefly, a lOkW peak power Hansch-type dye laser with a 0.5 cm" bandwidth is focused into a sodium heat-pipe cell. The laser intensity at the focus is 10 Mw/cm. The sodium cell is 20 cm in length. Argon at a few torrs pressure is used as a buffer gas. 

Whole-cell biocatalysts, organic solvents and, 16 412-413 Whole cells, 3 669-671 Whole-cell systems ionic liquids in, 26 897 Whole cluster pressing in white wine, 26 311 Whole-wheat flour, 26 279, 283 Whole yeast vaccines, 26 488 Who needs it concept, 24 190 Wicking limit, heat pipe, 13 230 Wicks... 

The vessel, as well as the wick, must be compatible with the working fluid. Where possible, the wick and vessel are made of the same material to avoid the formation of galvanic corrosion cells in which the working fluid can serve as the electrolyte. In addition to its role within the heat pipe, the vessel also serves as the interface with the heat source and the heat sink. 

FIGURE 15 A Paar XRK 900 cell mounted on a STOE theta-theta goniometer. Note the carefully heated piping for the feed. The bottom figure shows the sample holder with a Macor ceramic frit and the gas feed tubing forcing the feed gas through the catalyst bed. 

Arrowsmith et al used the crossed beam reaction F+Na— NaF+Na (3 P) to study radiative transfer and electronic energy transfer (E — E, V) in the Na (3 P)-1-NajCX S ) system. Previous studies of the Na2 system have utilized high-pressure cells or heat pipes in which radiation trapping is strong and Na + Na2 collisional energy transfer dominates. Time-resolved emission, following pulsed dye-laser excitation, has been used by Husain and his coworkers in a systematic survey of the excited-state behaviour of Mg(3 Pj), Ca(4 P,), and Sr(5 Pj). Dye-laser excitation of Mg vapour at 457.1 nm resulted in the observation of slow spontaneous emission from Mg(3 P,) which... 

The predicted distribution of net heat flux at the pipe surfaces is illustrated in Figure 11.19. It is interesting to note that the process fluid temperature distribution had a noticeable effect on the heat transfer. Cells A and B had the largest heat fluxes at the bottom, with considerably less heating at the top, whereas cells C and D had relatively uniform heat flux. It is also evident that, in cells A, B, and C, the peak heat flux occurred near the center of the tube bank (near the symmetry plane in the model). 

The sample cell system for GCIR consists of a micro-light-pipe cell, typically a 12 cm long silica tube with an i.d. of 1mm and reflective gold plated inner surfaces giving a cell volume of approximately 100 pi. The ends of the cell are fitted with spring loaded potassium bromide or zinc selenide windows (Figure 7.13b). The GC transfer line and cell are heated to a preset temperature between 50 and 350°C. 

For work with the Mg and Zn vapors, uniform vapor densities resulting in stable VUV emissions are obtained over periods of several hours with the use of double heat-pipe ovens while the heat-pipe oven for Hg vapor (Fig. 9) is a simple cell of pyrex glass. Liquid Hg and its vapor are confined to the central heated section by water-cooled jackets at each end which are tapered to return condensed Hg back to the hot zone. For generation of VUV radiation from 126 to 104.5 nm, a LiF plate a O.5 mn thick forms the exit window, and a vapor pressure of up to 95 torr is used with an equal pressure of He buffer gas. For XUV generation, X <... 

ChatiUon, C., Alhbert, M., Moracchioli, R., Rattoret, A. (1976) High-temperature studies by mass spectrometry use of heat pipe devices to maintain isothermal conditions in effusion cells. Journal of Applied Physics, 47, 1690-1693. 

LANL have an extensive history in developing heat pipes and their many applications within and out with chemical engineering applications. Current work is further developing the use of heat pipes in outer space although current applications are extremely vast from cooling CPUs to nuclear power cells. 

Supra J, JanBen H, Lehnert W et al (2013) Design and experimental investigation of a heat pipe supported external cooling system for HT-PEFC stacks. J Fuel Cell Sci Technol 10(5) 051002(l-7)... 

Mechanical Design. Typically, each battery will have a thermal sleeve around each cell. The cells are mechanicily restrained by clamping them in a precision-machined sleeve. These sleeves can be made of either a metal such as aluminum or a composite made in a manner to provide electrical isolation, high thermal conductivity and strength. The sleeve is isolated electrically from the cell by a blanket, such as CHO-THERM which allows thermal transfer, wrapped around the cylindrical portion of the cell between the cell and sleeve. The space between the sleeves, blanket and cell is normally filled with a material such as an RTV 566 to provide better thermal transfer as well as to bond the interfaces mechanically. The sleeves are then either attached mechanically to a base plate which is the interface to the satellite structure or are attached to an interface such as extruded heat pipe assemblies which are a part of the satellite structure. The exposed surfaces of the cells are protected by a coating of Solithane or a combination of paint on the cell pressure vessel and Solithane. The desired battery voltage defines the number of cells used for the assembly. 

Figure 2.1 shows a schematic diagram of this instrument [15]. Figure 2. la depicts a portionof the custom design of a commercial FUV spectrometer (KV-200, Bunko-Keiki, Tokyo, Japan). Figure 2.1b illustrates a flow cell unit formed between the sapphire IRE probe (7) and a fluorinated resin holder (8) enlarged from the area marked with a dashed line (part b) in Fig. 2.1a. The probe is fixed in place by the holder made by FIFE (8), with the flow sample cell formed by a space between the FIFE guide (9) and the aperture (1) of the probe. A liquid sample for measurement is drawn into the 2-mm-diameter aperture in the IRE probe. Air in the sealed instrument is purged with pure nitrogen gas. To control the sample temperature over the range of 5-80 °C, a Feltier element (10) is in contact with the probe holder (8) by a heat pipe (11).

The density N. can be determined from temperature and pressure measurements in absorption cells at thermal equilibrium. In the case of vaporized samples the vapor pressure has to be known [2.14]. In heat pipes [2.15] the vapor pressure is determined by the pressure of the noble gas which encloses the vapor. Since in heat pipes a definite zone with constant temperature and vapor pressure and with relatively sharp edges can be realized, these devices are very useful in the absorption spectroscopy of vapors [2.16a]. 

Both lasers are focused in a metal vapor cell to increase the power density which enhances the cross section for the LICET process. A convenient metal vapor cell is the "heat pipe" [12.40] where the vapor is confined within noble gas zones which prevent the metal vapor from diffusing to the cell windows. The.vapor pressure of the metal can be controlled by the noble gas pressure. For mixtures of two metals with different vapor pressures a double heat pipe has been developed [12.41] which allows maintainance of an equilibrium vapor mixture, where the ratio of p(A)/p(B) can be controlled within wide ranges. 

Lee (2010) Thermal Design Heat Sinks, Thermoelectrics, Heat Pipes, Compact Heat Exchangers, and Solar CellshyK. Lee, John Wiley Sons, Inc., Hoboken NJ. This book focuses on thermal engineering but we mention it here because it discusses several topics that are relevant to IR detection thermal engineering and cryogenics (relates to our Chapter 12), and his chapter on solar cells covers radiation (like our Chapter 2 - Radiometry), semiconductor physics (relates to our Chapters 4 and 5). Lee covers these topics succinctly but in more detail than we can provide here. 

Rohren-halter, m. tube (or pipe) holder, tube (or pipe) clamp, -kassie, /. pur ng cassia, -kleuune, /. tube clamp, -kiibler, m. tubular condenser, tube condenser tubular cooler, -libelle, /. spirit level, air level, -lot, n. pipe solder, -manna, /. flake manna, -nudeln, /.pi. macaroni, -ofen, m. tube furnace (for heating tubes liable to explosion) pipe still, -pulver, n. (Expl.) perforated powder, -struktur, /. tubular structure, -substanz, /. (Anat.) medullary substance, -trager, m. tube (or pipe) support, -wachs, n. petroleum ceresin. -werk, n. tubing piping tube mill, -wischer, m. tube brush, -wulst, n. tubular tore, doughnut , -zelle, /. tubular cell, specif. (Bot.) tracheid. 

In the past, copper was believed to be toxic to most microbiological species. Although this may be true in a test tube under laboratory conditions, it is not generally true in the real world. In this real world, microbial communities excrete slime layers which tend to sequester the copper ions and prevent their contact with the actual microbial cells, Aus preventing the copper from killing the microbes. Many cases of MIC in copper and copper alloys have been documented, especially of heat-exchange tubes, potable water, and fire protection system piping. 

Another requirement is a reduction in the generation of heat. Operation of any membrane under 90°C, even at 8 kA m-2, is very much desired for safety reasons and to prolong the life of the cell, piping or any other facilities subjected to high temperature. The ohmic drop beyond the membrane has been previously lowered by the narrowed gap separating the electrodes. This leaves further reduction of the ohmic resistance of the membrane to be achieved. 

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