Reversing thermometer

During the cruises in the 1950s and 1960s, oceanographic measurements were performed by means of reversing thermometers (Wolf, 1959) and Nansen bottles. Since 1974, the seawater was collected in a rosette of tube samplers combined with the CTD (Voigt et al., 1976 Seehase, 1980). Between 1951 and 1960/1961, currents were measured by means of Ekman-Merz current meters (Helm, 1968). 

Temperature Digital reversing thermometer (ocean origo) 2001-2005 0.02 C... 

Serial samplers as part of a sampling system (plus winch, hydrowire, bottom weight) used from ships, optionally supplied with reversing thermometers, triggered by messengers ... 

LVWS large volume water sampler, stainless steel, internal reversing thermometers, partition wall in the middle part, one opening with deflector plate, poor flushing characteristics 270,400 130, 220 ul (TO) HB... 

Accuracies achievable for measurements in the ocean are 0.002 mK for T, 0.05 % for P and 0.002 for S. Temperature and pressure sensors are calibrated in the laboratory. In situ comparison of the laboratory calibrations of these sensors only makes sense if additional sensors with digital output can be attached to the CTD. Die accuracy and stability of reversing thermometers and pressure sensors sometimes attached to rosette bottles is not suffi-... 

Total temperature is the temperature rise in the gas if its veloeity is brought to rest in a reversible adiabatie manner. Total temperature ean be measured by the insertion of a thermocouple, RTD or thermometer in the fluid stream. The relationship between the total temperature and static temperature can be given ... 

Because hydrolytic reactions are reversible, they are seldom carried out in batch wise processes [26,28,36,70]. The reactor is usually a double jacket cylindrical flask fitted with a reflux condenser, magnetic stirrer, and thermometer connected with an ultrathermostat. The catalyst is added to the reaction mixture when the desired temperature has been reached [71,72]. A nitrogen atmosphere is used when the reactants are sensitive to atmospheric oxygen [36]. Dynamic methods require more complicated, but they have been widely used in preparative work as well as in kinetic studies of hydrolysis [72-74]. The reaction usually consists of a column packed with a layer of the resin and carrying a continuous flow of the reaction mixture. The equilibrium can... 

The ideal (bio)chemical sensor should operate reversibly and respond like a physical sensor (e.g. a thermometer), i.e. it should be responsive to both high and low analyte concentrations and provide a nil response in its absence. One typical example is the pH electrode. In short, a reversible (bio)chemical sensor provides a response consistent with the actual variation in the analyte concentration in the sample and is not limited by any change or disruption in practical terms, responsiveness is inherent in reversibility. An irreversible-non-regenerable (bio)chemical sensor only responds to increases in the analyte concentration and can readily become saturated only those (bio)chemical sensors of this type intended for a single service (disposable or single-use sensors) are of practical interest. On the other hand, an irreversible-reusable sensor produces a response similar to that from an irreversible sensor but does not work in a continuous fashion as it requires two steps (measurement and renewal) to be rendered reusable. Figures 1.12 and 1.13 show the typical responses provided by this type of sensor. Note... 

Figure 3.1 Analytical working curve for a self-indexed luminescent thermometer based on the ratio between the measured excimer (E, 475 nm) and monomer (M, 375 nm) emission bands of l,3-b/s(l-pyrenyl)propane in [C4Cjpyr][Tf2Nj. The optical thermometer is perfectly reversible in the temperature range shown and highly precise, with the measured uncertainties in the ratio (1 /1 ) falling well within the symbol dimensions. The dashed curve represents the temperature uncertainty predicted from explicit differentiation of a sigmoidal fit to the calibration profile 5T = 0T/0R 5R where R = I /Iu- (Reprinted from Baker, G.A., Baker, S.N., and McCleskey, T.M., Chem. Commun., 2932-2933, 2003. Copyright 2003 Royal Society of Chemistry. With permission.)...

The spatial uniformity of temperature in the cell is difficult to determine, and we are not aware of a careful study of this problem. In most experiments, it is the temperature of the electrode-solution interface or that of the diffusion layer that is relevant. A possible internal thermometer could be created by measuring a temperature-sensitive voltammetric function, for example, the peak separation in the cyclic voltammogram of a reversible reaction, which is 2.22RT/ F. The resolution is not likely to be outstanding, but such a technique would probably allow detection of serious differences between the thermocouple reading and the actual temperature of the electrode-solution interface. 

Figure 9.1 Schematic diagram of the MBR65.1, Reaction vessel 2, top flange 3, cold-finger 4, pressure meter 5, magnetron 6, forward/reverse power meters 7, magnetron power supply 8, magnetic stirrer 9, computer 10, optic fibre thermometer 11, load matching device 12, waveguide 13, multi-modal cavity (applicator).

Equation (28) provides us with a means of defining a temperature scale that is as elegant as it is impractical. Our thermometer is a reversible heat engine, the efficiency of which we measure when it is operated between the temperature of interest and a reference temperature, defined as 273.15 K for an ice bath at 1 atm... 

A thermometer is based on a reversible heat engine, which operates between a boiling water bath and a heat reservoir at a lower temperature. The boiling water bath is defined to be at 373°. The temperature of the low temperature bath is determined from the efficiency with which the engine converts heat withdrawn from the boiling water bath to mechanical energy. Derive an explicit equation, Tc = /(e), from which the temperature of the low-temperature bath can be calculated. 

The demonstration of change in order/disorder, that is, a change in entropy, is present in everyday life. For example, the liquid mercury in a thermometer is made of small compact molecules (Fig. 16.1). When it is heated the molecules move faster they push their neighboring molecules away, the volume of the liquid expands, and the disorder, hence the entropy, increases. When the thermometer is cooled the opposite happens. Since there is relatively little interaction between the mercury molecules, the process is completely reversible. Not every material behaves this way. 

In 1742 Anders Celsius, a Swedish astronomer, developed the mercury centigrade thermometer. He chose the boiling and freezing points of water as calibration points. Curiously, he chose 0° for the high temperature and 100° for the low temperature. His choices were reversed in 1850 by Marten Stromer, also a Swedish astronomer. In 1948 the centigrade scale was officially renamed the Celsius scale. 

Linear expansion is most commonly used in bimetal spiral thermometers, which use two metals with different coefficients of expansion (see Fig. 2.29). The two metals can be welded, soldered, or even riveted together. As the metals are heated, the metal with the greater expansion will cause the spiral to flex open or close depending on which side the metal with the greater coefficient of expansion is on. A reverse in temperature will cause a commensurate reversal in the flexing. 

The nitrogen initially should come from the cold trap, Itself cooled under a nitrogen flush. At the end of the reaction, the flow of nitrogen should be reversed. This can be done by replacing the thermometer with a gas inlet tube. 

Figure 6. A representation of the isothermal recirculating, emulsification system (10). (1) Gear pump (2) reversible motor (3) revolution counter (4) emulsifying chamber (5) heat exchanger (6) thermometer (7) plastic tubings.

---