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The regenerator used in Stirling cryocoolers is the crucial component, which has a flow conduit through the porous matrix material. Various parameters affect the performance of the regenerator, of ...

The performance of the Stirling cryocoolers essentially depends on the performance of the regenerator. The regenerator used in Stirling cycles has, essentially, having a high surface area and heat capacity leading to large heat transfers. Packed Metal wool, packed wire Mesh screen, randomly packed sphere, porous metal structure are some of the common types of regenerator matrix materials. Wire mesh based regenerators matrix material are common as it provides high heat transfer area with lower entropy generation rate. The paper study in detail the design and structural parameters of mesh type regenerators of Stirling cryocoolers. The work also involves the design, development and attempt to fabricate a prototype porous type Stirling Cryocooler regenerator with a porosity range of 69–71% using Direct Metal Laser Sintering (DMLS) techniques of additive manufacturing, which will enable to use it as a retrofit regenerator to the existing Stirling cycle based liquid nitrogen plants.

The performance of the Stirling cryocoolers is directly affected by the performance of the regenerator. An attempt to build a structured porous regenerator for Stirling cryocooler of required geometry, packing density and porosity using additive manufacturing. The paper analyses in detail the numerical analysis of a structured porous regenerator designed for additive manufacturing with a porosity range of 69-71%, using ANSYS 18.1 Computational Fluid Dynamics (CFD) and the experimental test results of additively manufactured regenerator in a cryocooler

Regenerators are used in cryogenics for nitrogen and helium liquefaction through reversed Stirling cycle to achieve a low operating temperature of 40 K. An ideal regenerator has critical properties such as low thermal conductivity, optimum porosity, high heat transfer, and specific heat. In general, the matrix of the porous materials is in the form of wire mesh, fibrous wool, granules, or foams. The recent technological development in additive manufacturing (AM) allows it to extend its application to porous structure-based energy exchanging devices. Direct metal laser sintering (DMLS) is one of the AM processes used to fabricate complex geometry with uniform porosity, of considerably low cost compared with the conventional processes. This paper presents the development of an experimental setup to investigate the steady axial pressure drop analysis through various types of regenerators. These regenerators have been tested for multiple working fluids such as Argon and Helium gas at room temperature. The axial pressure drop results of the additive regenerator have been compared with the woven wire mesh and copper wool type of regenerators. The additively manufactured regenerator has a lower pressure drop of 9% and 14% than the copper wool and woven wire mesh type regenerators.

Low temperature facility (LTF) of Tata Institute of Fundamental Research, (TIFR) Mumbai, India has been operating and maintaining helium liquefiers, nitrogen generators for more than five decades. LTF is one of the largest cryogenic facilities in India under the R&D Sectors. Cryogens being produced and dispensed to about 45 research laboratories within TIFR including some critical cryogen-using setups, magnetometer facility, homemade setups, various departments such as Nuclear and Atomic Physics, Chemical Sciences, Biological Sciences too use cryogens in a large quantities. In order to fulfill the above large cryogens demand and to maintain the supply in an uninterrupted manner, LTF implemented various automation in terms of cryogen distribution, Dewar tracking, reporting, etc. The paper will present our experience, architecture, methodology adopted, and automation implemented in the cryo-distribution at TIFR along with the proposed work.

In contrast to real-time data acquisition systems employing a minicomputer with a real-time multiprogramming operating system, this paper describes the design and development of a high throughput data acquisition system using an IBM compatible PC/AT, high speed sampling A/D converter, and dual ported FIFO RAM buffers, in the MS-DOS environment. Data acquisition software is developed in Turbo Pascal with a few in-line machine language procedures.

This paper presents the controller synthesis and real-time simulation of the final net-recovery phase of a remotely piloted vehicle (RPV). The recovery configuration imposes certain requirements on the controller. Further, the inherent geometry and structure of the aircraft impose restrictions on certain state variables. The mixed H/sub 2//H/sub /spl infin// approach was adopted to synthesize the controller. The synthesized controller was discretized using standard techniques; a real-time simulation was then conducted using the detailed model of the RPV on a stand alone DSP device and the controller hooked up to the DSP through a PC.

Low temperature facility of Tata Institute of Fundamental Research Mumbai provides liquid helium and liquid nitrogen along with the various other cryogenic support services to many facilities and laboratories of the institute. On the total annual liquid nitrogen consumptionover 3,00,000 liters, majority supply is utilized by the Pelletron LINAC Facility, for cooling the thermal shields of the quarter wave resonating cavities, distribution line of the cryostats, precooling of helium refrigerator and for the beam hall experiments. Liquid nitrogen is produced by STIRLIN-8 plant with a liquefaction rate of 110 liter per hour at an elevated pressure of 2barg. The vacuum jacketed and super-insulated liquid nitrogen transfer line of about 310 meters long interconnects plant and SC LINAC accelerator. The paper present the in depth details about the cryogen distribution, VJ piping and also the technical modifications and various automation carried out by us on the liquid nitrogen plant.

In an attempt towards the development of modern, model and paperless cryogenic facility, the Low Temperature Facility of Tata Institute of Fundamental Research, at Mumbai, India; carried out many automation works using programmable logic controller (PLC) and other modern electronic tools, with the objective of bringing the entire plant operation to your palm whenever and wherever you are. Efficiency in the plant operation by keeping a watch on the plant healthiness, advance indication about the possible plant problem by means of pre-warning alarms, so that the remedial action can be taken well prior to the actual failure affects the plant operation, reduction in plant down time were achieved by the automation works. Large size in our cryogen production, controlling the complicated helium liquefier, meeting the uninterrupted supply of cryogen to the users on "any time availability basis," safety in handling cryogens and high pressure gas, effective usage of limited skilled manpower etc., all these requirements call for the definite need of modern electronic gears and gadgets. This paper will describe in details about the automation works carried out at our cryogenic facility at TIFR.

A potential industrial outlet for o-cumidine as an intermediate for new monoazo and disazo solvent dyes is reported. New solvent dyes prepared from o-cumidine had much better solubilities than the corresponding commercial dyes derived from o-toluidine. Absorption maxima of the o-cumidine-based dyes were generally comparable with those of analogous o-toluidine derivatives, although a large difference was apparent in one disazo system studied. Although the monoazo dyes showed somewhat lower tinctorial strength, the disazo dyes exhibited better tinctorial power. The performance of 4-o-cumylazo-o-cumidine as a Fast Base was comparable with that of Fast Garnet GBC Base.

The UV-visible spectra of several 3-substituted 2-aryl phenalen-1-ones and dyes such as C.I. Disperse Red 303 which incorporate the phenalen-1-one as the basic chromophore are recorded and colour-chemical constitution aspects of these compounds have been studied. The fluorescence spectral data of C.I. Disperse Red 303 revealed that the component 1 was more fluorescent than the component 2, although 2 was more bathochromic compared with 1. The difference in the fluorescence intensity has been explained on the basis of difference in polarity of the carbonyl group brought about by the positional difference of the electron donor ring sulphur atom. Confirmation of these observations was obtained by X-ray crystallographic study of component 1 of C.I. Disperse Red 303.

India produces per day about 44 000 tonnes of urban refuse having a pollution load of 59·4–68·2 tonnes. The annual nutrient potential of this waste is 0·084, 0·036 and 0·043 million tonnes of N, P and K, respectively. The refuse from Calcutta alone represents 0·005 million tonnes of N and 0·002 million tonnes each of P and K out of the total. The waste, in combination with sewage sludge, on aerobic incubation produces a compost with 1·34% nitrogen and a C/N ratio of 12·17 within 90 days. The compost contains 1·64 ppm copper and 0·84 ppm zinc, but compost-manured water contained only 0·08 and 0·03 ppm of the metals, respectively. The mineralisation rate of 30·51% on the twentieth day and the highest BOD 5 load of 18·93 mg/litre on the tenth day indicate a moderate transformation rate of the compost and low toxic effects of copper and zinc. The impact of the compost on the diurnal oxygen changes in the pond water was found to be non-detrimental to aquatic life. The compost-manured water showed an overall increase of 33% over the control in its nutrient levels, primary productivity and plankton production.

The reaction of 1-aminoanthraquinone ( 1 ) and 1,5-diaminoanthraquinone ( 2 ) with α,β-unsaturated ketones in the presence of anhydrous aluminium chloride led to the facile formation of new substituted dihydroanthrapyridine-quinones 3 in a one-stage synthesis. 2-Aminoanthraquinone failed to react under identical conditions. The investigations were extended to the reaction of 1 and 2 with acrylonitrile, methyl acrylate, methyl methacrylate and diethyl ethoxymethylenemalonate to yield the substituted aminoanthraquinones 4 . The new compounds were evaluated as disperse dyes on polyester.

Penicillin mycelium is an industrial fermentation waste with 80% moisture and high BOD 5 load (15 000–20 000 mg litre −1 ). The waste, with an N:P:K ratio of 5·99:2·31:1·63 and neutral pH, can be considered to be a rich and balanced organic manure. The potential of the waste for aquaculture as a manure has been studied in this work. The mean C/N ratio of 11·27 advocates its direct incorporation into the water body but its organic carbon level (67·20%) indicates a delayed optimum mineralisation. The biodegradability rate of the waste could not be perceptibly accelerated by Ca ++ , Mn ++ and Mo +++ . The study on the impact of the waste on the abiotic and biotic character of the host water body indicates that its response as a fertiliser is high. Its sustained high BOD 5 load is responsible for a delayed response.

The standard potential at 25°C of the electrode system Pc−Hg2Pc2Hg, where Pc denotes picrate, has been determined as 492.4 mV using sodium-responsive glass electrodes in cells without liquid junction. The value was confirmed by measurements of the solubility of mercury(I) picrate, determined spectrophotometrically, which lead to a value for the solubility product of 10−10,31 mol3 dm−9.

Design features of a baloon borne instrument for the study of cosmic X-rays, are described. Advantages of equatorial location for investigations in X-ray astronomy are discussed. Details of the X-ray telescope and associated instrumentation are described. A summary of the performance of the instrument and results obtained in three balloon flights are presented.

A simple method of electronically eliminating radiation pick-up due to spark chamber discharges, in the electronic logic of a counter telescope, is described.

A spectrophotometric method using 0.5M hydrochloric acid in methanol as solvent, has been used for the determination of 2-amino-3H-phenoxazin-3-one [APZ], occurring as a coloured impurity in o-aminophenol [OAP]. This impurity dissolves in the acid medium, giving a stable red solution which complies with Beer's law. The method can be applied to the determination of APZ in technical samples of OAP.

A potential industrial outlet for o-cumidine as an intermediate for new monoazo and disazo solvent dyes is reported. New solvent dyes prepared from o-cumidine had much better solubilities than the corresponding commercial dyes derived from o-toluidine. Absorption maxima of the o-cumidine-based dyes were generally comparable with those of analogous o-toluidine derivatives, although a large difference was apparent in one disazo system studied. Although the monoazo dyes showed somewhat lower tinctorial strength, the disazo dyes exhibited better tinctorial power. The performance of 4-o-cumylazo-o-cumidine as a Fast Base was comparable with that of Fast Garnet GBC Base.