Additional Cooler Research Articles

Fast-Tracking an FLNG Relocation in Malaysia

This article, written by JPT Technology Editor Judy Feder, contains highlights of paper OTC 30440, “Floating LNG 1 Relocation: Another World’s First,” by Muhammad Fakhruddin Jais, Wan Mahsuri Wan Hashim, and Ariff Azhari Ayadali, Petronas, et al., prepared for the 2020 Offshore Technology Conference Asia, originally scheduled to be held in Kuala Lumpur, Malaysia, 17–19 August. The paper has not been peer reviewed. Copyright 2020 Offshore Technology Conference. Reproduced by permission. Floating liquefied natural gas (FLNG) allows LNG to be processed hundreds of kilometers away from land to unlock gas reserves in remote and stranded fields previously uneconomical to monetize. The complete paper describes the operator’s fast-tracking of a 450-km FLNG unit relocation from Sarawak to Sabah offshore Malaysia. The time from selecting the new field to unloading LNG at the new location was 13 months. The complete paper discusses pre-execution and engineering studies, relocation preparation and execution, and challenges encountered, including timeline, cost minimization, and manning. Introduction Since 2016, Petronas has operated its first floating LNG production, storage, and offloading facility offshore Sarawak. During the tenure of operation, cargo was delivered successfully to customers worldwide. An opportunity to help a different gas supplier monetize another stranded field offshore Sabah, approximately 450 km away from the unit’s original location, presented itself. The new opportunity was deemed feasible for several reasons. - The identified location is still within Malaysian waters and thus is subject to similar authority and regulations. - Operation within the same country ensures common support from vendor and contractors to some extent. - The two fields have similar gas profiles and water depth. The project team determined that these factors would result in minimal modification at both FLNG and up-stream facilities to meet minimum shut-down from project sanction until first LNG cargo was produced. Pre-Execution and Engineering Studies To fast-track the project, an evaluation was conducted of the new feed-gas composition and modification of both up-stream and FLNG facilities. Long-lead items (LLIs) were identified, and studies were conducted to secure the items. One of the identified LLIs was the flexible pipeline from the upstream facilities to the FLNG. A flow-assurance study covered the steady-state and transient operation for the flexible line. This study confirmed the size of the pipeline and defined the functional requirement for the flexible pipeline procurement. Among the key parameters identified were the pipeline’s thermal conductivity and design pressure. During the feasibility stage, a steady-state study was conducted to determine the length of the flexible line in order to meet the landing pressure and temperature at the FLNG. Instead of requiring additional cooler, the flexible line was extended 2 km to take advantage of the Joule-Thomson cooling effect resulting from the pressure drop across the pipeline. In addition to defining the LLI properties, the flow-assurance study also examined the transient operation for both upstream and FLNG upon the closure of the riser shutdown valve. The study assessed flow-assurance issues, such as hydrates and adequacy of the slug receiver during the transient operation, that might arise, and defined the start-up and commissioning sequence for the facilities.

МОДЕРНІЗАЦІЯ ЕНЕРГО-ФУНКЦІОНАЛЬНОЇ СХЕМИ ПРОЦЕСУ ПАСТЕРИЗАЦІЇ ЯБЛУЧНОГО СОКУ

This paper describes the technological scheme of apple juice pasteurization process are considered. The issues of modernization of the existing technological scheme of apple juice pasteurization process are considered. Namely, an improved energy-functional scheme of a combined type with complete heat recovery was obtained. The value of technical and economic indicators is determined. A comparative analysis of the received scheme with the scheme with an additional cooler was carried out. The chilling machine is a combined type, ie, with simultaneous working out of heat and cold for the needs of production. Therefore, it is more efficient than the refrigeration system with an additional cooler, however, it has a compressor with an electrical power of 173 kW and heat exchange equipment of greater power. A variant of a circuit solution may be suitable for implementation in those enterprises where, in addition to pasteurization of process streams, a large amount of hot water with a temperature potential of up to 90 ºС is required. Both circuit solutions that have been developed and analyzed are conceptual and can be adjusted in terms of energy efficiency and basic technical and economic indicators in the design and implementation process. They can also be used in the design of new industries, where there are pasteurization and cooling processes and in the reconstruction of old enterprises in order to improve their energy efficiency.

Integration of electronic system with electro-thermally cooled IR detector: thermal analysis

The paper presents thermal investigations of an idea of encapsulation in common, miniature package both preamplifier circuit and infrared photodetector cooled with the aid of four-stage thermoelectric module. Conducted numerical simulations show that the presence of electronics at printed circuit board with either ceramic or laminate substrate negligibly affects operation of thermoelectric cooler and hence, the operating conditions of the detector. Higher thermal loads are reported when placing wideband electronic system on the additional thermoelectric module. Even though, such solution reduces temperature difference between infrared sensor and the other part of electronics, additional cooler increases the amount of heat that must be dissipated from the package to the ambient.

Instantaneous pressure measurement in pulsating high temperature internal flow in ducts

Research tasks in internal combustion engines often require instantaneous pressure measurement of the gases inside the exhaust manifold including absolute value information. In such environment, flow operation includes high temperature and extremely pulsating conditions. The work described in the paper identifies the problems that arise when acquiring absolute pressure with a piezoresistive transducer. A methodology based on using an additional cooler for a piezoresistive sensor placed between the duct and the original sensor cooler adaptor is proposed for dynamic pressure measurement. Specific tests have been performed in cold and hot pulsating flow in order to check the influence of the additional cooler geometry. It is possible to remove the effect of the additional cooler but the procedure depends on the pressure in the duct. If relevant frequencies in the signal are similar to the natural frequency of the cooler, a simple filtering technique is not recommended. In this case, direct application of the acoustic theory inside ducts allows the reconstruction of the instantaneous pressure in the duct. Comparisons between the reconstructed pressure and measurements carried out with piezoelectric transducers, which do not capture the absolute value of the signal but can be placed in the duct without using an additional cooler, in hot and pulsating flow are presented. Results confirm that the method for pressure reconstruction from additional cooled piezoresistive transducers provides accurate information for instantaneous pressure measurement in hot and pulsating flow conditions inside ducts.

Efficiencies and emissions of a 192 kWel Otto engine CHP‐unit running on biogas at the research station “Unterer Lindenhof”

An Otto engine CHP‐unit running on biogas has been under investigation for more than two years. Within this time data regarding temperatures, energy flows, biogas composition, emissions etc. were collected, and this paper presents some of the results. In detail, electric and thermal output are discussed for one full year. From these data the monthly electric availability of the unit can be calculated, which ranges from 84.0 to 96.4%. In addition, the utilization of the heat produced by the CHP‐unit during one year is displayed. It was found that 18.2% of the heat was needed for heating purposes within the biogas plant, and 64.5% of the heat could be supplied to the district heating system. Hence, 17.3% of the useful heat had to be released to the ambient air by an additional cooler. Regarding emissions, a strong impact of the excess air ratio on emissions of NOX has been observed. Moreover, the effect on electric efficiency is outlined in this paper. As known from theory, the experimental results revealed that an increase in the excess air ratio helps to lower NOX‐emissions, while electric efficiency is reduced by this means.

Increase of Operating Current of the LHD Helical Coils by Upgrading the Cooling System

The Large Helical Device (LHD), one of the world's largest superconducting systems, has been operated for the research of fusion plasma since 1998. The toroidal field of almost 3 T is made by a pair of pool-cooled helical coils. When they were cooled with saturated liquid helium at 4.4 K, a normal-zone had been induced several times in their innermost layer at the higher current than 11.0 kA. In order to improve the cryogenic stability by lowering temperatures, an additional cooler with two-stage cold compressors was installed at the inlet of the coil. The inlet and outlet temperatures of the coils are successfully lowered to 3.2 K and 3.8 K, respectively, with a mass flow of 50 g/s. Stable operation of the subcooling system has been established, and the operating current for the plasma experiments can be increased up to 11.4 kA.

Redshifted emission lines and radiative recombination continuum from the Wolf-Rayet binary θ Muscae: evidence for a triplet system?

We present XMM-Newton observations of the WC binary 0 Muscae (WR 48), the second brightest Wolf-Rayet binary in optical wavelengths. The system consists of a short-period (19.1375 days) WC5/WC6 + 06/07V binary and possibly has an additional O supergiant companion (09.5/B0Iab) which is optically identified at a separation of ∼46 mas. Strong emission lines from highly ionized ions of C, O, Ne, Mg, Si, S, Ar, Ca and Fe are detected. The spectra are fitted by a multi-temperature thin-thermal plasma model with an interstellar absorption N H = 2-3 x 10 21 cm -2 . Lack of nitrogen line indicates that the abundance of carbon is at least an order of magnitude larger than that of nitrogen. A Doppler shift of ∼630 km s -1 is detected for the O VIII line, while similar shifts are obtained from the other lines. The reddening strongly suggests that the emission lines originated from the wind-wind shock zone, where the average velocity is ∼600 km s -1 . The red-shift motion is inconsistent with a scenario in which the X-rays originate from the wind-wind collision zone in the short-period binary, and would be evidence supporting the widely separated O supergiant as a companion. This may make up the collision zone be lying behind the short-period binary. In addition to the emission lines, we also detected the RRC (radiative recombination continuum) structure from carbon around 0.49 keV. This implies the existence of additional cooler plasma.

Results of the Excitation Test of the LHD Helical Coils Cooled by Subcooled Helium

Large helical device, the largest superconducting stellarator, has been operated for the research of fusion plasma since 1998. The toroidal field of almost 3 T is produced by a pair of pool-cooled helical coils, in the innermost layers of which a normal-zone had been induced several times at the bottom of the coil at higher currents than 11.0 kA. Since the field is not the highest there, the local cooling conditions are probably deteriorated by bubbles gathered by buoyancy. In order to improve the cryogenic stability by subcooling, an additional cooler with two-stage cold compressors was installed at the inlet of the coil in 2006. The inlet and outlet temperatures of the coils were successfully lowered to 3.2 K and 3.8 K, respectively, with a mass flow of 50 g/s. In spite of a half charging rate to reduce AC losses, a normal-zone was induced near the top of the coil at 11.45 kA. It propagated to one side and stopped near the inner equator, where the field is the highest. In comparison with the stability tests with a model coil, the local temperatures of the innermost layers near the top is considered to have been raised up to almost the saturated temperature of 4.4 K by charging. The excitation method was revised to waiting cool-down at 11.0 kA, and the excitations up to 11.5 kA have been attained.

Achievement of high availability in long-term operation and upgrading plan of the LHD superconducting system

The Large Helical Device (LHD) is not only the largest stellarator for the research of fusion plasma near a reactor region but also the largest superconducting system. Availability higher than 98% has been achieved in the long-term continuous operation both in the cryogenic system and in the power supply system. It is due to the robustness of the systems and efforts of maintenance and operation. One big problem is the shortage of cryogenic stability of a pair of pool-cooled helical coils. Composite conductors had been developed to attain sufficient stability at high current density. However, it was revealed that a normal-zone could propagate below the cold-end recovery current by additional heat generation due to the slow current diffusion into a thick pure aluminium stabilizer. Besides, a novel detection system with pick-up coils along the helical coils revealed that normal-zones were initiated near the bottom of the coil where the field is not the highest. Therefore, the cooling condition around the innermost layers, the high field area, will be deteriorated at the bottom of the coil by bubbles gathered by buoyancy. In order to raise the operating currents, methods for improving the cryogenic stability have been examined and stability tests have been carried out with a model coil and small coil samples. We selected a method to lower temperatures of the coil and an additional cooler has been installed at the inlet of the coil. The outlet temperatures of the coil have been successfully lowered to 3.8 from 4.4 K of the saturated temperature, as planned.

A Study of Synthetic and Observed Hα Spectra of TT Hydrae

The formation and properties of accretion disks and circumstellar material in Algol-type systems are not very well understood. In order to study the underlying physics of these structures, we have calculated synthetic Hα spectra of TT Hya, which is an Algol-type eclipsing binary with an accretion disk. Both the primary and secondary stars were considered in the calculations, as well as a disk surrounding the primary. The Roche model for the secondary star was assumed. The synthetic spectra cover all the phases, including primary eclipse, and are compared with the observed spectra. The influence of various effects and free parameters of the disk on the emerging spectrum was studied. This enabled us to put some constraints on the geometry, temperature, density, and velocity fields within the disk. Differences found between the observed and synthetic spectra unravel the existence of a gas stream, as well as a hotter disk-gas interaction region. An additional cooler circumstellar region between the C1 and C2 Roche surfaces is suggested to account for various observed effects. A new computer code called SHELLSPEC was created for this purpose and is briefly described in this work as well. It is designed to solve simple radiative transfer along the line of sight in three-dimensional moving media. The scattered light from a central object is taken into account assuming an optically thin environment. Output intensities are then integrated through the two-dimensional projection surface of a three-dimensional object. The assumptions of the code include LTE and optional known state quantities and velocity fields in three dimensions.

Mapping small-scale temperature and abundance structures in the core of the Perseus cluster

We report further results from a 191 ks Chandra observation of the core of the Perseus cluster, Abell 426. The emission-weighted temperature and abundance structure is mapped detail. There are temperature variations down to ~1 kpc in the brightest regions. Globally, the strongest X-ray surface brightness features appear to be caused by temperature changes. Density and temperature changes conspire to give approximate azimuthal balance in pressure showing that the gas is in hydrostatic equilibrium. Si, S, Ar, Ca, Fe and Ni abundance profiles rise inward from about 100 kpc, peaking at about 30-40 kpc. Most of these abundances drop inwards of the peak, but Ne shows a central peak, all of which may be explained by resonance scattering. There is no evidence for a widespread additional cooler temperature component in the cluster with a temperature greater than a factor of two from the local temperature. There is however evidence for a widespread hard component which may be nonthermal. The temperature and abundance of gas in the cluster is observed to be correlated in a manner similar to that found between clusters.

Study on the Noise Reduction of Refrigerant Flow at Outlet of Capillary Tube. Relationship between Two-Phase Flow and Noise Issue.

Recently, Noise reduction for indoor air conditioning units has become necessary. This paper discusses : (1) Exploration at the noise source of capillary tube and outlet plenum. (2) the reason for high-and low-frequency noise of fluid flow based on R22 fluid flow pattern. (3) the method of noise reduction dependent on supercooling of refrigerant R22 by setting an additional cooler up-stream of the capillary tube. According to the above items, it is necessary for the noise reduction to control bubble contents at an outlet of the capillary tube.

Surface exploration of the Theistareykir high-temperature geothermal area, Iceland, with special reference to the application of geochemical methods

The surface exploration of the Theistareykir high-temperature geothermal area in northeast Iceland is reported. The results of stable isotope and Cl determinations are used to characterise the origin of the fluid, gas geothermometers to indicate underground flow temperatures, and major gas ratios. Rn, and Hg concentrations to infer permeability, boiling conditions, upflow locations, and flow directions. These results are used in conjunction with geological and geophysical studies to construct a model of the geothermal system, whose main features are upflow zones under the northeast and southwest parts of the geothermally active surface area, with a cooler zone between, which could result from poorer permeability and additional cooler inflow. A suggestion is made as to the siting of the first exploratory well in the Tjarnarás area close to the southwesterly upflow area.

Phenology of fynbos, renosterveld and subtropical thicket in the south eastern Cape

Qualitative and quantitative phenological observations were made on 173 species in eight communities in climatically similar sites. Results indicated that in species growing on different substrates, soil type had a minimal effect on phenophases. Phenophase patterns were analyzed by grouping species into growth form classes. Geophytes and annuals grew from autumn to spring. The majority of restioids and C 3 grasses grew most in the cool wet seasons. C 4 grass species showed either a summer growth season or an additional cooler growth season; the former species do not occur westwards in the winter rainfall region while the latter do. Most succulents grew in autumn and spring while two species also grew in summer. Small leaved sclerophyll shrubs grew throughout the year and/or showed a summer growth peak. The former pattern is consistent with a ‘generalist strategy’ but the latter is not readily explained because of summer drought conditions. Subtropical large leaved sclerophyll shrubs showed irregular growth and reproduction whereas large leaved proteoid shrubs grew in summer and autumn. In all shrub growth forms maximum leaf loss occurred in summer. Phenophase patterns were explained in terms of ecophysiological factors but biological and historical factors were also considered.