Constant Temperature Bath Research Articles

Burnett PVT Measurements of Hydrogen and the Development of a Virial Equation of State at Pressures up to 100 MPa

PVT properties were measured for hydrogen by the Burnett method in the temperature range from 353 K to 473 K and at pressures up to 100 MPa. In the present Burnett method, the pressure measurement was simplified by using an absolute pressure transducer instead of a differential pressure transducer, which is traditionally used. The experimental procedures become easier, but the absolute pressure transducer is set outside the constant temperature bath because of the difficulty of its use in the bath, and the data acquisition procedure is revised by taking into account the effects of the dead space in the absolute pressure transducer. The measurement uncertainties in temperature, pressure, and density are 20 mK, 28 kPa, and 0.07 % to 0.24 % (k = 2), respectively. Based on the present data and other experimental data at low temperatures, a virial equation of state (EOS) from 220 K to 473 K and up to 100 MPa was developed for hydrogen with uncertainties in density of 0.15 % (k = 2) at P ≤ 15 MPa, 0.20 % at 15 MPa 40 MPa, and this EOS shows physically reasonable behavior of the second and third virial coefficients. Isochoric heat capacities were also calculated from the virial EOS and were compared with the latest EOS of hydrogen. The calculated isochoric heat capacities agree well with the latest EOS within 0.5 % above 300 K and up to 100 MPa, while at lower temperatures, as the pressure increases, the deviations become larger (up to 1.5 %).

Burnett Method with Absolute Pressure Transducer and Measurements for PVT Properties of Nitrogen and Hydrogen up to 473 K and 100 MPa

A measurement method for PVT properties of high-temperature and high-pressure gases was developed by simplifying the Burnett method and revising the data acquisition procedure. Instead of a differential pressure transducer, which is traditionally used, an absolute pressure transducer is used in the present method, and the measurement of pressure becomes easier. However, the absolute pressure transducer is placed outside the constant temperature bath because of the difficulty of its use in high-temperature surroundings, and some parts with different temperatures from the sample vessels exist as dead space. The present method takes into account the effect of the dead space in the data acquisition procedure. Nitrogen was measured in the temperature range from 353 K to 473 K and at pressures up to 100 MPa to determine the apparatus constants, and then, hydrogen was measured at 473 K and up to 100 MPa. The determined densities are in agreement within uncertainties of 0.07% to 0.24% (k = 2), both with the latest equation of state and existing measured data.

Evaluation of thermal performance of energy textile installed in Tunnel

A new geothermal energy source obtained from a tunnel structure has been studied in this paper. The geothermal energy is extracted through a textile-type ground heat exchanger named "Energy Textile" that is fabricated between a shotcrete layer and guided drainage geotextile. To evaluate the thermal performance of the energy textile, a test bed was constructed in an abandoned railway tunnel located in Seocheon, South Korea. The thermal conductivity of shotcrete and lining samples which were prepared in accordance with a common mixture design was measured in laboratory. An overall performance of the energy textile installed in the test bed was evaluated by carrying out a series of in-situ thermal response tests. In addition, a 3-D finite volume analysis (FLUENT) was adopted to simulate the operation of the ground heat exchanger being encased in the energy textile with the consideration of the shotcrete and lining thermal conductivity, fluid circulation rate, the existence of groundwater and the arrangement of circulation pipes. The results of numerical analyses show that the energy textile exhibits better thermal performance under the following conditions: the thermal conductivity of the tunnel wall is relatively high, and the velocity of the circulated fluid in the energy textile is low. Based on the in-situ thermal response tests, a numerical analysis is performed to simulate the performance of the system under the field condition. In addition, to observe the long-term thermal behavior, the difference in the temperatures of the inlet and outlet fluid of the energy textile is monitored using a constant-temperature water bath and a real simulation system for cooling operating. From the long-term monitoring, results show that the average heat exchange amount of the energy textile (2 unit) was 592–713 W, that is 0.08–0.09 RT for 1 unit.

Spectroscopic studies on the influence of 10 mol% of glycine on nonlinear optical crystal l-valinium picrate

Nonlinear optics is a fascinating field, which plays a vital role in the emerging field of photonics and optoelectronics. A new nonlinear optical crystal of glycine mixed l-valine picrate (GVP) have been grown from saturated aqueous solution by slow evaporation method at a temperature of 36 °C using a constant temperature bath of accuracy of ±0.01 °C. The synthesized organic optical material has been purified by repeated recrystallization. Single crystal X-ray diffraction analysis has been made to determine the cell parameters and it confirms the crystal lattice to be orthorhombic. UV–vis-NIR spectrum have recorded for GVP crystals in the range from 190 nm to 1100 nm and it is found that the crystal has cut-off at 450 nm. Fourier transform infrared transmission has confirmed the presence of the functional group present in the title compound. The spectrum has been recorded by KBr pellet technique. The 1H and 13C NMR spectra have been recorded to elucidate the molecular structure of GVP crystals. The second harmonic generation (SHG) of the grown crystal have been confirmed by Kurtz–Perry method using Nd:YAG laser as source.

Thermal Characteristics of a Sealed Glass-Water Heat Pipe from 0 °C to 60 °C

Investigations into the thermal characteristics of glass-water heat pipes from 0 °C to 60 °C were carried out at the National Institute of Metrology (NIM), China. In this paper, studies on a glass-water heat pipe with four thermometer wells are described. The experimental results indicated that the temperature stability and uniformity of the thermometer well of the glass-water heat pipes are within several tenths of a millikelvin when the heat pipes are immersed in a constant-temperature liquid bath, since they have a highly effective thermal conductivity. They are able to maintain a constant temperature by the absorption or liberation of the latent heat of evaporation to attenuate temperature fluctuations of the surroundings. Also, above 0 °C to 30 °C, the temperature stability of the thermometer well of the glass-water heat pipe is better than 0.1 mK for approximately 16 h. The maximum temperature differences among the thermometer wells are less than 5.5 mK when the water heat pipes operate in the range from 0 °C to 60 °C. Therefore, water heat pipes are very promising to improve the performance of liquid baths and to accurately calibrate thermometers by comparison.

ChemInform Abstract: 1H-Bicyclo(3.1.0)hexa-3,5-dien-2-one. A Strained 1,3-Bridged Cyclopropene.

and CD3C6D5 (0.100 M) in benzene were prepared in an inert atmosphere box, placed in a vacuum transfer tube, degassed, and stored under argon. Weighed samples of (TMP)Rh-CH, were placed into vacuumadapted NMR tubes, dissolved in benzene, and irradiated in a Rayonnet photoreactor for 6 h (A 2 350 nm) to form (TMP)Rh'. The solvent was then pumped off and 0.5 mL of the toluene stock solution syringed in under argon. The NMR tubes were then attached to a vacuum line and subjected to three freeze-pumpthaw cycles and sealed under vacuum. The samples were subsequently heated in a constant-temperature oil bath, and the concentration of the constituents was periodically monitored by 'H NMR. Linearity of plots for [(TMP)Rh']-' versus time and variation of the toluene concentration indicate that the rate law for reaction 5 is second order in [(TMP)Rh'] and first order in toluene (ratef(,) = k5[(TMP)Rh*]2[CH~C6H,]). [(TXP)Rh], with CH,. Relative concentrations of [(TXP)Rh],,

Burning characteristics of palm-oil biodiesel under long-term storage conditions

The influences of oxidative variables on the burning characteristics of palm-oil biodiesel were investigated experimentally in this study. Biodiesel, which is composed of monoalkyl esters of long-chain fatty acids, generally has an inferior oxidative stability than petrodiesel. Hence, the long-term oxidative stability of palm-oil biodiesel has received much industry attention because it is used widely as an alternative to pure diesel fuel. Palm-oil biodiesel was stored in a constant-temperature water bath at either 60 °C or 20 °C continuously for 3000 h to observe the variation in its oxidative degradation and burning characteristics, such as carbon residue and the amount of heat released, with storage time. The effect of antioxidant addition on the burning characteristics was also investigated. The experimental results reveal that the palm-oil biodiesel suffered greater oxidative degradation at higher storage temperatures and in the absence of an antioxidant, which resulted in a faster decrease in the amount of heat released as the storage time elapsed. The addition of the chain-breaker antioxidant BHT effectively broke the peroxidation reaction mechanism and hence significantly retarded the decrease in heat release. The oxidative stability of the palm-oil biodiesel was worst at a higher storage temperature, a longer storage time, and in the absence of an antioxidant, which caused the more extensive formation of sediments of oxidative products and hence a larger carbon residue after burning. The greater oxidative degradation also caused the more extensive decomposition of unsaturated fatty acids into oxidative products, which decreased the flash point and the cetane index of the fuel.

Flow boiling enhancement on a horizontal heater using carbon nanotube coatings

In this study we measure the flow boiling heat flux on a horizontal heater that is heated from below. The horizontal heater consists of either a bare silicon wafer or a silicon wafer that is coated with multi walled carbon nanotubes (MWCNT). The silicon wafer is clamped on a constant heat flux type calorimeter consisting of a vertical copper cylinder with embedded cartridge heaters and K-type thermocouples. De-ionized (DI) water was used as the test fluid. The calorimeter apparatus is housed in a test section with glass walls for visual observation. The liquid is pumped from a constant temperature bath to maintain a fixed subcooling during the experiments under steady state conditions. Boiling curves (wall heat flux as a function of heater temperature) were obtained for different flow rates and liquid subcooling. Experiments were performed for two different flow rates and two different liquid subcoolings. Flow boiling heat flux was enhanced by as much as 180% at boiling incipience for silicon substrates coated with carbon nanotubes. MWCNT was less effective in enhancing heat flux as the flow rate and liquid subcooling was increased. This anomalous behavior was explained using flow boiling models reported in the literature.

Growth and characterization of 2-amino-4-picolinium 4-aminobenzoate single crystals

The organic material of 2-amino-4-picolinium 4-aminobenzoate (C 6H 9N 2 +·C 7H 6NO 2 −) was synthesized and grown as single crystals at room temperature by slow evaporation solution growth technique in the constant temperature bath (±0.01 °C) using ethanol as solvent. The grown crystals were characterized by XRD and FT-IR spectral analyses. The melting point, density, UV–visible spectral studies were carried out for the grown crystals. The theoretical factor group analysis predicts 372 internal modes of vibration and optical modes in the grown title compound. The second harmonic generation (SHG) output of 2-amino-4-picolinium 4-aminobenzoate was recorded by Kurtz–Perry powder technique and it is found to be 355 mV at a given pulse energy of 1.45 mJ/s and for urea the SHG output was 525 mV. The dielectric behaviour of 2-amino-4-picolinium 4-aminobenzoate was investigated with different frequencies and temperatures.

Temperature- and magnetic-field-controlled magnetic pole reversal in a molecular magnetic compound

A highly reversible (bipolar) switching of magnetization in a Prussian blue type molecular magnet Cu0.73Mn0.77[Fe(CN)6]⋅zH2O using low magnetic fields is demonstrated. The studied molecular compound also shows both positive and negative magnetocaloric effects below its magnetic ordering temperature. A molecular field theory calculation has also been done to explain the observed temperature dependent magnetization reversal behavior. Possible applications of the magnetic pole reversal phenomenon in magnetoelectronic and magnetocaloric devices such as magnetic memory and magnetic cooling/heating based constant temperature bath have been revealed.

A HISTORICAL ATLAS OF OBJECTIVITY

The mythical scientist in early twentieth-century America cut a lone figure, “impersonal as the chill northeast wind” and “oblivious of everything save his experiment.” He toiled through the night in his laboratory, “a place unimpressive and unmagical save for the constant-temperature bath with its tricky thermometer and electric bulbs,” as if working in the lab were a prayer that promised illumination—“alone, absorbed, [and] contemptuous of academic success and of popular classes,” he knew all about material forces, but he was blind to the vital force that created all others. Accustomed to the “beautiful dullness of long labors,” he remained “illimitably ignorant” of literature, art, and music. He believed that unerring techniques in experimentation, impartial observations, and exquisitely minute calculations would bring progress—a steady march toward the truth. He chose the highest calling in the world because he was “intensely religious—so religious that he will not accept quarter-truths, because they are an insult to his faith.” He was “so devoted to Pure Science . . . that he would rather have people die by the right therapy than be cured by the wrong. Having built a shrine for humanity, he wanted to kick out of it all mere human beings.” This autocratic figure, brilliantly insane and tyrannically honest, embodied the cult of science and objectivity.

Flow Loop Experiments Using Polyalphaolefin Nanofluids

Experiments were performed using a flow-loop apparatus to explore the performance of nanofluids in cooling applications. The experiments were performed using exfoliated graphite nanoparticle fibers suspended in polyalphaolefin at mass concentrations of 0.6 and 0.3 %. The experimental setup consisted of a test section containing a plain offset fin cooler apparatus (gap or nongap fin), which was connected to a flow loop consisting of a gear pump, a shell and tube heat exchanger (that was cooled or heated by a constant temperature bath chiller/heater), and a reservoir. Experiments were conducted using nanofluid and polyalphaolefin for two different fin strip layouts. Heat transfer data were obtained by parametrically varying the operating conditions (heat flux and flow rates). The heat transfer data for nanofluids were compared with the heat transfer data for neat polyalphaolefin fluid under similar conditions. The change in surface morphology of the fins was investigated using scanning electron micrography. The nanofluid properties were measured using rheometry for the viscosity, differential scanning calorimetry for the specific heat, and laser flash apparatus for the thermal diffusivity. It was observed that the viscosity was ∼10 times higher for nanofluids compared with polyalphaolefin and increased with temperature (in contrast, the viscosity of polyalphaolefin decreased with temperature). The specific heat of nanofluids was found to be 50% higher for nanofluids compared with polyalphaolefin and increased with temperature. The thermal diffusivity was found to be 4 times higher for nanofluids compared with polyalphaolefin and increased with temperature. It was found that, in general, the convective heat transfer was enhanced by ∼10% using nanofluids compared with using polyalphaolefin. Scanning electron micrography measurements show that the nanofluids deposit nanoparticles on the surface, which act as enhanced heat transfer surfaces (nanofins).

Influence of an experimental palatal plate on thermal perception

This study aimed to examine how coverage of the hard palate by an experimental palatal plate influenced thermosensation. A total of 20 young adult volunteers were recruited from Osaka University Graduate School of Dentistry. An experimental palatal plate, 1.5mm in thickness, was made for each subject from acrylic resin. The stimulus water were either warmed to 40, 42, 44, 46, or 48 degrees C or cooled to 30, 26, 22, 18, or 14 degrees C in a constant-temperature water bath, and the control water were maintained at 37 degrees C. Subjects were instructed to retain the control water in their mouths for 5 s, then to spit it out and to repeat with the stimulus water. They then rated the intensity of stimulation of warmth or cold compared to the control water by the magnitude estimation method. Each stimulus was administered three times in random order. Two experimental conditions were set: with and without the experimental palatal plate. Perceived thermal intensity was measured as the slope of the regression line for each condition (with or without the experimental palatal plate, cold or warmth). There was a significant difference between with and without the experimental palatal plate; the regression slope with the plate was shallower than that without the plate (warmth perception with plate=0.55+/-0.21 vs. warmth perception without plate=0.70+/-0.23, P<0.05; cold perception with plate=-0.33+/-0.14 vs. cold perception without plate=-0.39+/-0.11, P<0.05). The findings suggested that a denture covering the hard palate obstructs thermal perception.

An experimental study of axial conduction through a thermosyphon pipe wall

The effect of the axial conduction through the pipe wall on the performance of a thermosyphon was experimentally investigated in this study. Two 2-phase closed thermosyphons were tested; each had the same dimensions, materials and partially filled with R134a. The only difference between them was that one had a thermal break within the adiabatic section that resisted axial conduction between the evaporator and the condenser sections. The thermosyphons were heated by a constant-temperature hot bath and cooled by water via a concentric heat exchanger. The experiments were performed for different bath temperatures and different fill ratios. It was found that the axial conduction through the pipe wall caused an increase in the overall heat transfer coefficient, evaporation heat transfer coefficient and condensation heat transfer coefficient of the thermosyphon. However, the fraction of heat transfer associated with axial conduction decreased as the heat flux increased. For small heat flux ( T b = 30 °C), the increment of the evaporation and condensation heat transfer coefficient contributed by axial conduction reached 100% and 25%, respectively. For high heat flux ( T b = 60 °C), the increment was negligible (less than 1%).

Effects of Oxidation during Long-term Storage on the Fuel Properties of Palm Oil-based Biodiesel

Because palm-oil biodiesel is widely used as an alternative to petrodiesel, its long-term fuel properties have become of great concern to the fuel industry. In this study, we investigated the dependence of the fuel properties of palm-oil biodiesel on its oxidative degradation. We considered storage temperature, storage time, and the addition of antioxidant as possible factors influencing oxidative instability. Palm-oil biodiesel was continuously stored in a constant-temperature water bath at 20 or 60 °C for 3000 h to allow for variations in oxidative degradation and fuel properties such as kinematic viscosity and acid value to be observed as the storage time elapsed. The oxidative degradation of palm-oil biodiesel was caused by the peroxidation chain mechanism, which started with a hydrogen-abstraction reaction in the methylene group (−CH2−) from polyunsaturated fatty acids, leading to the formation of hydroperoxides. In turn, the fuel properties of the biodiesel became degraded. The extent to which there was chemical reactivity in the peroxidation reaction was dominated by the level of unsaturation of the biodiesel. Moreover, a higher storage temperature and a longer storage time significantly accelerated the rate at which the peroxidation chain reaction proceeded in the palm-oil biodiesel. In contrast, the addition of a chain-breaker type antioxidant was found to be effective in reducing the lipid oxidation rate and thus retarding the fuel degradation rate of the palm-oil biodiesel. Palm-oil biodiesel to which an antioxidant was added and which was stored at a lower temperature of 20 °C was observed to have the highest level of oxidative stability and the lowest rate of decrease in both unsaturated fatty acids and iodine value as storage time increased. The same sample of palm-oil biodiesel was also found to have the lowest rates of increase in water content, kinematic viscosity, acid value, and peroxide value as storage time increased.

Thermo-hydraulic characterisation of soft rock by means of heating pulse tests

Low-permeability clayey rocks, currently considered as suitable host rocks for high-level nuclear waste disposal, pose a challenge for the determination of thermal, hydraulic and mechanical properties. A thermo-hydraulic stainless steel cell, capable of testing undisturbed soil or rock cores 70 mm in diameter and 100 mm long, has been developed and used to identify thermal properties (conduction coefficient, heat capacity, thermal expansion), permeability (derived from gas and water tests) and swelling behaviour. The cell is operated in a constant-temperature bath. Miniature pore water pressure transducers and thermocouples are installed in different positions of the specimen. Strain gauges attached to a reduced-thickness ring section of the cell provide information for swelling pressure determinations. Temperature changes are applied by a thin heater centred in the axis of the specimen. A computer code was specifically written to perform and control experiments. Air permeability is determined by means of a pulse decay technique, whereas liquid permeability is directly interpreted at steady-state conditions. However, back-analysis of the complete measured response of the specimen (pore pressures, temperatures and swelling pressures) provides the best procedure for identifying properties. A testing protocol involving a sequence of undrained and drained heating tests has been developed to determine, in an ordered way, the thermal properties and the permeability. The procedure requires the concourse of a coupled thermo-hydro-mechanical code in order to simulate test results. The program CODE_BRIGHT, developed at UPC, was used for these purposes. The procedure was applied to the identification of the thermal properties of Opalinus clay shale.

Experimental and computational study of constrained melting of phase change materials (PCM) inside a spherical capsule

An experimental and computational investigation directed at understanding the role of buoyancy-driven convection during constrained melting of phase change materials (PCM) inside a spherical capsule is reported. The computations are based on an iterative, finite-volume numerical procedure that incorporates a single-domain enthalpy formulation for simulation of the phase change phenomenon. A Darcy’s Law-type porous media treatment links the effect of phase change on convection. Paraffin wax n-octadecane was constrained during melting inside a transparent glass sphere through the use of thermocouples installed inside the sphere. The melting phase front and melting fraction of the PCM are analyzed and compared with numerical solution obtained from the CFD code Fluent. Following a short period of symmetric melting due to prominence of diffusion, expedited phase change in the top region of the sphere and a wavy surface at the bottom of the PCM are observed. The computational predictions point to the strong thermal stratification in the upper half of the sphere that results from rising of the molten liquid along the inner surface of the sphere thus displacing the colder fluid. The waviness and excessive melting of the bottom of the PCM is shown to be underestimated by the experimental observation. This discrepancy is linked to the use of a support structure to hold the sphere. Measured temperature data and computational results near the bottom indicate the establishment of an unstable fluid layer that promotes chaotic fluctuations and is responsible for waviness of the bottom of the PCM. On the other hand, the comparison between the measured and computed temperatures in the top half of the sphere show the stable nature of the molten liquid layer. The computational results start to deviate from the thermocouple readings as one moves lower from the top of the sphere. This delay in predicting the melting instant is linked to the thermal stratification within the “constant temperature bath” that encloses the capsule.

Experimental investigation of micro-scale temperature transients in sub-cooled flow boiling on a horizontal heater

Surface temperature fluctuations that occur locally underneath departing bubbles in pool boiling are shown to result in local heat transfer coefficients ranging from 1 to 10 kW/cm 2. These estimates were reported in the literature involved both numerical and experimental approaches. Significantly higher heat fluxes are associated with flow boiling than pool boiling under similar conditions of wall superheat and liquid subcooling (e.g. at boiling inception and at critical heat flux). These enhancements are primarily caused by the convective transport, acceleration/distortion of the bubble departure process as well as the resultant potential enhancement of the local surface temperature fluctuations. In this study we measure the surface temperature fluctuations using temperature micro/nano-sensors fabricated on a silicon wafer during flow boiling on the silicon wafer which is heated from below. The silicon wafer is clamped on a constant heat flux type calorimeter consisting of a vertical copper cylinder with embedded cartridge heaters and K-type thermocouples. Micro/nano-thermocouples (thin film thermocouples or “TFT”) are fabricated on the surface of the silicon wafer. High speed data acquisition apparatus is used to record temperature data from the TFT at 1 kHz. A fluorinert was used as the test fluid (PF-5060, manufacturer: 3M Co.). The calorimeter and surface temperature measurement apparatus is housed in a test section with glass walls for visual observation. The liquid is pumped from a constant temperature bath to maintain a fixed subcooling during the experiments under steady state conditions. The transient temperature data from the FFT array during flow boiling on the silicon wafer is analyzed using fast Fourier transform (FFT). The FFT data is analyzed as a function of the wall heat flux and wall superheat. The number of temperature peaks in the FFT data is observed to increase with increase in wall heat flux and the peaks are found to cover a wider spectrum with peaks at higher frequencies with enhancement of heat flux. The surface temperature fluctuations, especially at small length and time scales, are perturbed potentially by the coupled hydrodynamic and thermal transport processes, resulting in enhanced local and global heat flux values. Boiling incipience condition and the flow boiling data are compared with correlations reported in the literature.

Modeling of water absorption of Botswana bambara varieties using Peleg’s equation

Hydration kinetics of five bambara seed varieties from Botswana was studied by soaking in water at temperatures 25–100 °C in constant-temperature water bath for 0.5–24 h using Peleg equation. Peleg’s equation adequately described the hydration characteristics of bambara seeds under the experimental condition with the mean relative percentage deviation modulus ( E) of less than 10% for each variety. For each variety, Peleg’s rate constant K 1 decreased significantly as the hydration temperature was increased from 25 to 100 °C suggesting a corresponding increase in the initial water absorption rate. Peleg capacity constant K 2 increased with increase in temperature (25–75 °C) and dropped at 100 °C in all varieties, demonstrating that the water absorption rate increased and water absorption capacity decreased with increase in temperature. While an E a of 37.83, 39.60, 33.02, and 33.33 kJ/mol was calculated for NTSR, BotR, DipC1, DipC2 bambara seeds, respectively, a lower value of 16.46 kJ/mol was obtained for AS17. The negative values of enthalpy (Δ H ∗) for all the variety indicate that changes during the hydration of bambara seeds are associated with exothermic and energetically favorable transformation. The higher values of E a and free energy of activation (Δ G ∗) for NTSR, BotR, DipC1, and DipC2 indicate that the seeds experience a large change and hydration was more influenced by temperature. However, the lower value of E a and the negative values of entropy of activation (Δ S ∗) for AS17 indicate that the seeds were more thermally stable and hydration changes was less influenced by temperature. The optimum soaking time for bambara seeds for all the varieties appear to be 6 h at temperature ⩽75 °C.

A study of cooling rate of the supercooled water inside of cylindrical capsules

An experimental apparatus was developed to investigate the supercooling phenomenon of pure water inside cylindrical capsules used for cold storage process. The Phase Change Material (PCM) used was distilled water. The external coolant material was a water–alcohol mixture (50% vol.), controlled by a constant temperature bath (CTB) in four fixed values (−4 °C, −6 °C, −8 °C, and −10 °C). Temperatures varying with time were measured inside and outside the capsule. Cylindrical capsules with internal diameter of 30 mm, 45 mm, and 80 mm, with 1.5 mm wall thickness were made in aluminum, bronze or acrylic materials. The Cooling Rate (CR) was investigated for different positions on the internal wall of the capsule, for different external coolant temperatures ( T c), different capsules diameters and different materials. The results showed that the cooling rate is a strong function of the angular position on the internal wall, the coolant temperature, the capsule material, and the capsule's diameter.