Evaporative Coolant Research Articles

Effects of NSPRI wall-in-wall evaporative coolant on physical properties of stored tomato

Nigerian Stored Products Research Institute developed a wall-in-wall evaporative cooling system for the storage of fresh fruits and vegetables. This is an effort in mitigating post-harvest loss of fruits and vegetables. The effect of the cooling system on the physical properties of tomatoes was investigated using ambient shelf storage as a control. Weight loss, firmness loss and colour changes of tomatoes were the major physical properties studied. Tomatoes were stored for 24 days. There was significantly higher loss in weight of tomatoes stored in ambient (68%) than those of the evaporative coolant (32%). There was significant higher loss in firmness of the tomato stored in ambient (95%) those in evaporative cooling system (58%). Tomatoes stored in evaporative cooling system retained better color while those under ambient became darkened at the end of the storage period.

Effects of NSPRI wall-in-wall evaporative coolant on physical properties of stored tomato

Effects of NSPRI wall-in-wall evaporative coolant on physical properties of stored tomato

On Coolant Flow Rate-Cutting Speed Trade-Off for Sustainability in Cryogenic Milling of Ti-6Al-4V.

Application of cryogenic fluids for efficient heat dissipation is gradually becoming part and parcel of titanium machining. Not much research is done to establish the minimum quantity of a cryogenic fluid required to sustain a machining process with respect to a given material removal rate. This article presents an experimental investigation for quantifying the sustainability of milling a commonly used titanium alloy (Ti–6Al–4V) by varying mass flow rates of two kinds of cryogenic coolants at various levels of cutting speed. The three cooling options tested are dry (no coolant), evaporative cryogenic coolant (liquid nitrogen), and throttle cryogenic coolant (compressed carbon dioxide gas). The milling sustainability is quantified in terms of the following metrics: tool damage, fluid cost, specific cutting energy, work surface roughness, and productivity. Dry milling carried out the at the highest level of cutting speed yielded the worst results regarding tool damage and surface roughness. Likewise, the evaporative coolant applied with the highest flow rate and at the lowest cutting speed was the worst performer with respect to energy consumption. From a holistic perspective, the throttle cryogenic coolant applied at the highest levels of mass flow rate and cutting speed stood out to be the most sustainable option.

Sustainable hole-making in a titanium alloy using throttle and evaporative cryogenic cooling and micro-lubrication

• Effectiveness of using evaporative and throttle cryogenic coolants in titanium drilling is investigated. • Throttle cooling favored tool life, productivity, cleanliness, energy consumption, and process cost. • Evaporative cooling caused thick adhesion on drills and did not support any sustainability measure. • Micro-lubrication also favored most of the sustainability measures but at a low productivity level. • Pecking should not be used in drilling of low to medium depth holes in titanium alloys. Titanium, being a structural material, undergoes drilling process frequently for its engineering applications. The superior mechanical properties of titanium alloys make hole-making a highly unsustainable process. The process is marred by high cutting forces, intense tool damage, high energy consumption, poor hole quality, and high process cost. The work presents an approach for viable and cleaner drilling of the difficult-to-cut material by investigating the effects of micro-lubrication and the following two options of cryogenic cooling: (1) evaporative cooling using liquid nitrogen and (2) throttle cooling using compressed carbon dioxide gas. Additionally, the effects of cutting speed and pecking – a technique actualized by rapidly retracting the twist drill by 2 mm at two levels of depth during thru-cutting of the holes – are also quantified. Pecking is not found to be favorable to any of the evaluated sustainability measures. Of the three cutting fluids testes, throttle cryogenic cooling yielded the most advantageous results. The coolant, because of its effective heat dissipation capability, yielded superior outcomes with respect to all the sustainability measures except surface quality. Micro-lubrication proved to be beneficial, at the low level of cutting speed, to specific cutting energy, surface quality, and process cost. Evaporative cryogenic cooling did not yield promising results. The runs employing evaporative coolant or the high level of cutting speed experienced thicker tool adhesions whereas those utilizing pecking showed signs of intense progressive wear. Moreover, the thrust force data indicated occurrence of thermal softening of the work material as the drills progressed through the hole-cutting process. From the holistic perspective of sustainability, it is recommended to adopt throttle cryogenic cooling, a medium-to-high level of cutting speed, and no-pecking for hole-making in the titanium alloy.

Research on Resistance Characteristics of the Self-circulating Evaporative Cooling System for Traction Transformer

Compared with the tradition cooling technology, the evaporative cooling technology has the advantage of energy-saving, safety and reliability. So a self-circulating evaporative cooling structure was proposed. The narrow flow channels were designed between disk-type windings. The evaporative coolant flows in the narrow flow channels and takes away the heat loss through phase transition. In this paper the resistance characteristics of the system were studied through experiment based on the 900kVA transformer prototype.

Electrocaloric cooling over high device temperature span

Summary Electrocaloric cooling demonstrates direct electricity utilization and high energy efficiency, and is often proposed as an environmentally benign, solid-state alternative to the conventional vapor compression cooling technology. As a result, the fabrication of effective electrocaloric materials and engineering of electrocaloric cooling devices have attracted increasing attention in the cooling community. However, the limited material adiabatic temperature change under safe operation field poses a major challenge to practical electrocaloric cooling device development, since real-world applications usually require device temperature span over 20 K. This perspective presents recent efforts devoted to design electrocaloric cooling devices based on active heat regeneration and cascading approaches; both strategies have achieved significant device temperature lift ~10 K with adiabatic temperature change of 2~3 K. The strategies discussed in this work are broadly applicable to the design of efficient and compact cooling systems.

Influence of Poultry Manure on Growth and Fruit Yield of Selected Pepper Species and Their Qualities after Storage in Various Structures

The production of pepper is low due to decrease in fertility of soil and inadequate storage structures. The study was aimed at evaluating the growth, yield and storage qualities of selected pepper varieties as influenced by poultry manure and storage structures in Ibadan, Nigeria. A field experiment was carried out at Department of Agronomy, University of Ibadan between November, 2017 and April, 2018 growing season. Two varieties of pepper (Capsicum annum and Capsicum frutescens) were used, with four treatments consisting of different rates of poultry manure. Controls of 0 g of poultry manure (T1), 12.5 g (T2), 25 g (T3) and 37.5 g (T4) were laid out in a complete randomised design and replicated four times. Storage experiment was carried out in the Department and at Nigeria Stored Products Research Institute (NSPRI), Ibadan in June, 2018. The storage experiment comprised of four treatments with ambient condition (open shelf), wet basket, Evaporative Coolant Structure (ECS/Pot-in-pot), and plastic crates used as storage structures, laid out in a completely randomised design and replicated three times. The physical parameters obtained in days in storage (DIS) included weight loss (%), firmness, freshness, among others. Data observed were subjected to analysis of variance (ANOVA) and means separated using least significant difference (LSD) at p>0.05. The result obtained showed that pepper growth was enhanced using Capsicum frutescens under 25 g poultry manure application rate which resulted to superior pepper yield. The combination of pot-in-pot with sawdust as storage structures enhanced the storage qualities of pepper fruits within the two weeks of storage. Although, the different manure treatments had no significant effect on the postharvest quality of pepper, the ECS can be effectively used in the storage of pepper fruits in order to improve postharvest quality, extend shelf life and enhance affordability of the commodity at all seasons.

Comparison of the use of evaporative coolants and ice packs for the management of preoperative edema and pain in ankle fractures: a prospective randomized controlled trial.

The use of evaporative coolants in the management of acute musculoskeletal injury has received increasing attention recently. However, its efficacy compared with conventional cryotherapy in treating injured human subjects remains unclear. The purpose of this study is to compare the efficacy of evaporative coolants with that of ice packs in preoperative management of edema and pain in patients with an ankle fracture. Sixty-three patients in need of surgical treatment for ankle fracture were randomly assigned to either an evaporative coolant group or an ice pack group. Both treatments were applied for 5 days after injury and outcomes were measured daily. The primary outcome was a reduction in edema as measured by the figure-of-eight-20 method and the secondary outcome was measured by visual analog scale (VAS) for pain. Two-way analysis of variance with repeated measures showed no significant group effect and no significant group-by-time interaction in terms of reduction of edema and VAS score for pain between two groups. No adverse effects were reported in either group. Evaporative coolants exhibited comparable efficacy to ice packs in preoperative cryotherapy of ankle fractures without adverse effects. While evaporative coolants are more expensive than ice packs, they can present a viable option for cryotherapy. Level I, prospective randomized study.

Influence of chitosan edible coating on postharvest qualities of Capsicum annum L. during storage in evaporative cooling system

Chitosan is a biopolymer edible coating which can act as physical barrierwhen coated on fruits and efficiently alter their internal atmosphere and delay the ripening process. This study evaluates the usage of chitosan (CH) as edible coating to extend the shelf life of green bell pepper. Physiochemical and microbial analysis of the green bell pepper was conducted during evaporative coolant structure storage (ECS). The effect of chitosan coating on green bell pepper significantly delayed a loss in firmness, weight loss, and vitamin C content and inhibited the growth of heterotrophic bacteria, mesophilic bacteria, yeast and mould during the five weeks of storage. On the whole, this study established that edible coating from chitosan could form a natural and permanent replacement to the chemically preservatives used for postharvest management of green bell pepper.

Applications and perspectives of gas analysis based on sonar instrumentation

We have developed ultrasonic instrumentation to simultaneously monitor flow and composition in a variety of gas mixtures. Flow and mixture composition are respectively derived from measurements of the difference and average of sound transit times in two opposite directions in a flowing process gas blend. Gas composition is then determined from an automated comparison of the measured sound velocities with a velocity/composition database.Continuous, real-time precision measurements of binary gas mixtures are required in many applications. While the most natural application of this instrumentation is in the analysis of such mixtures, analysis of mixtures with additional components is also possible, as discussed in this paper.In the ATLAS experiment at CERN, several instruments are presently used in the Detector Control System. Three instruments monitor octafluoropropane (C3F8, R218) and carbon dioxide (CO2, R744) coolant leaks into the nitrogen-purged envelopes surrounding elements of the inner silicon tracker. Precision in molar concentration of better than 2.10−5 is routinely seen in mixtures of C3F8 in nitrogen in the presence of known concentrations of the third party gas CO2.Two further instruments are used to monitor the new 60 kW thermosiphon C3F8 evaporative coolant recirculator which exploits the 90 m depth of the ATLAS pit to circulate coolant without the need for pumps or compressors in the primary loop. These instruments are used to verify the absence of air leaks in the thermosiphon cooling circuit and to measure the vapour-phase coolant flow in real-time.This instrumentation is also used to measure zeotropic fluorocarbon blends containing C3F8 and up to 25% hexafluoroethane (C2F6, R116), achieving a precision around 0.16% in the range 0–25% C2F6. We also report on measurements of heat transfer coefficient in these blends: our experimental data were compared to several empirical correlations, with typical differences less than 10%.This analysis technique, targeting binary pairs of gases of dissimilar molecular weight, is particularly promising for mixtures of anesthetic gases, including in the developing area of anesthesia using xenon. The instrument and its various applications will be discussed.

Shelf-life of pepper fruits as influenced by harvesting methods and storage conditions

The effects of stage of ripeness at harvest, harvesting methods and storage conditions on storability of organic long Cayenne pepper fruits were investigated. Fruits were harvested with or without pedicels, at 10 or 100% ripe stage and stored at ambient conditions (21.9-33.5°C and 58-62% relative humidity (RH), in refrigerator (4.0°C and 40-45% RH) or in evaporative coolant structure (10.0-15.8°C and 70-75% RH). Postharvest quality was assessed using percentage weight loss; and general appearance on a scale of 1-4. Means were separated by Duncan multiple range test (DMRT) at p<0.05. Refrigerated fruits had significantly lower WL between 3 and 30 days in storage (DIS) compared to those in ambient conditions or evaporative coolant structure. Between 9 to 30 DIS, fruits harvested with pedicel intact exhibited significantly lower weight loss compared to those without pedicels. Furthermore, fruits harvested at 10% ripeness had significantly lower WL of than those harvested at 100% ripeness during the storage period.

Parotid and mandibular gland secretion by red kangaroos, Macropus rufus, in response to heat stress

Salivary flow rates from ipsilateral parotid and mandibular glands were measured in conscious red kangaroos over a 70–90-min period during episodes of saliva spreading induced by heat stress. At the onset of saliva spreading, mandibular flow rose rapidly to plateau at 1.12 ± 0.10 mL min–1 for the collection intervals after the first 10 min of licking. Parotid flow increased more slowly and progressively, reaching secretion rates similar to those of the mandibular gland after 40 min of saliva spreading, exceeding mandibular flow after 70 min and showing no indication that it had reached maximum secretion at 90 min of saliva spreading. The ion concentrations of both parotid and mandibular salivas during saliva spreading were similar to those previously reported for parasympathomimetic stimulation. The low osmotic concentration of mandibular saliva relative to plasma (40%) makes it a functionally better evaporative coolant than parotid saliva, which was nearly isosmotic with plasma. The increased production of hydrogen ions associated with the increased secretion of bicarbonate by the parotid gland would tend to offset the respiratory alkalosis due to panting thereby helping to maintain acid/base balance during periods of prolonged heat stress.

LHCb VELO upgrade

The upgrade of the LHCb experiment, scheduled for LHC Run-III, scheduled to start in 2021, will transform the experiment to a trigger-less system reading out the full detector at 40MHz event rate. All data reduction algorithms will be executed in a high-level software farm enabling the detector to run at luminosities of 2×1033cm−2s−1.The Vertex Locator (VELO) is the silicon vertex detector surrounding the interaction region. The current detector will be replaced with a hybrid pixel system equipped with electronics capable of reading out at 40MHz. The upgraded VELO will provide fast pattern recognition and track reconstruction to the software trigger. The silicon pixel sensors have 55×55μm2 pitch, and are read out by the VeloPix ASIC, from the Timepix/Medipix family. The hottest region will have pixel hit rates of 900Mhits/s yielding a total data rate of more than 3Tbit/s for the upgraded VELO. The detector modules are located in a separate vacuum, separated from the beam vacuum by a thin custom made foil. The foil will be manufactured through milling and possibly thinned further by chemical etching.The material budget will be minimised by the use of evaporative CO2 coolant circulating in microchannels within 400μm thick silicon substrates. The current status of the VELO upgrade is described and latest results from operation of irradiated sensor assemblies are presented.

The LHCb VELO upgrade

The upgrade of the LHCb experiment, planned for 2019, will transform the experiment to a trigger-less system reading out the full detector at 40MHz event rate. All data reduction algorithms will be executed in a high-level software farm. The upgraded detector will run at luminosities of 2×1033cm−2s−1 and probe physics beyond the Standard Model in the heavy flavour sector with unprecedented precision. The Vertex Locator (VELO) is the silicon vertex detector surrounding the interaction region. The current detector will be replaced with a hybrid pixel system equipped with electronics capable of reading out at 40MHz. The detector comprises silicon pixel sensors with 55×55μm2 pitch, read out by the VeloPix ASIC, based on the TimePix/MediPix family. The hottest region will have pixel hit rates of 900Mhits/s yielding a total data rate more than 3Tbit/s for the upgraded VELO. The detector modules are located in a separate vacuum, separated from the beam vacuum by a thin custom made foil. The detector halves are retracted when the beams are injected and closed at stable beams, positioning the first sensitive pixel at 5.1mm from the beams. The material budget will be minimised by the use of evaporative CO2 coolant circulating in microchannels within 400μm thick silicon substrates.

Upgrade of the LHCb Vertex Locator

The upgrade of the LHCb experiment, planned for 2018, will transform the entire readout to a trigger-less system operating at 40 MHz. All data reduction algorithms will be executed in a high-level software farm, with access to all event information. This will enable the detector to run at luminosities of 1–2 × 1033/cm2/s and probe physics beyond the Standard Model in the heavy sector with unprecedented precision.The upgraded VELO must be low mass, radiation hard and vacuum compatible. It must be capable of fast pattern recognition and track reconstruction and will be required to drive data to the outside world at speeds of up to 2.5 Tbit/s. This challenge is being met with a new Vertex Locator (VELO) design based on hybrid pixel detectors positioned to within 5 mm of the LHC colliding beams. The sensors have 55 × 55 μm square pixels and the VELOPix ASIC which is being developed for the readout is based on the Timepix/Medipix family of chips. The hottest ASIC will have to cope with pixel hit rates of up to 900 MHz.The material budget will be optimised with the use of evaporative CO2 coolant circulating in microchannels within a thin silicon substrate. Microchannel cooling brings many advantages: very efficient heat transfer with almost no temperature gradients across the module, no CTE mismatch with silicon components, and low material contribution. This is a breakthrough technology being developed for LHCb.LHCb is also focussing effort on the construction of a lightweight foil to separate the primary and secondary LHC vacua, the development of high speed cables and radiation qualification of the module.The 40 MHz readout will also bring significant conceptual changes to the way in which the upgrade trigger is operated. Work is in progress to incorporate momentum and impact parameter information into the trigger at the earliest possible stage, using the fast pattern recognition capabilities of the upgraded detector.The current status of the VELO upgrade will be described together with a presentation of recent beam-test results.

The silicon vertex locator for the LHCb upgrade

The upgrade of the LHCb experiment, planned for 2018, will transform the entire readout to a triggerless system being read out at 40MHz. The upgraded silicon vertex detector (VELO) must be light weight, radiation hard, and compatible with LHC vacuum requirements. It must be capable of fast pattern recognition, fast track reconstruction and high precision vertexing. This challenge is being met with a new VELO design based on hybrid pixel detectors positioned to within 5mm of the LHC colliding beams. The detector will be shielded from the beam by a ~300μm thick aluminium foil. Evaporative CO2 coolant circulating in micro-channels embedded in a thin silicon substrate will be used for cooling.

English

Shelf-life of five horticultural produce were studied. These include three leafy vegetables: Telfairia occidentalis, Celosia argentea and Amaranthus cruentus and two fruit vegetables: Lycopersicum esculentum and Abelmuschus esculentus. The layout plan of the experiment was a 3x2 factorial in a completely randomized design and each treatment replicated three times. The two factors examined were moisture barrier at three levels namely: thick lining, thin lining and non-lining. The other factor included initial moisture content of the produce, namely, turgid and partially wilted. Partial wilting of the produce was achieved by exposing freshly harvested materials at ambient temperature to dry for 45 min. During this period, about 20% of the moisture content was lost. Eighteen (18) vegetable baskets which work on the principle of evaporative cooling system were used. Each type of produce was stored at a time inside the vegetable basket. Some quantity of each produce were kept on the laboratory benches to serve as controls. Data recorded includes length of storage of produce, severity of disease infection, visual quality, disease incidence, ambient temperature and relative humidity of the storage baskets. The result indicates that there was a significantly higher relative humidity (P< 0.05) in the lined baskets than in the non-lined baskets. Consequently, the shelf-life of produce in lined basket was prolonged. Turgid produce had better quality retention and stored much longer than partially wilted produce. Generally, the evaporative coolant baskets provided an average temperature of 3°C lower than the ambient condition. The shelf-life of leaf vegetables T. occidentalis, C. argentea and A. cruentus was extended appreciably for 78 days compared to the controls.

Micro channel evaporative CO2 cooling for the upgrade of the LHCb vertex detector

Local thermal management of detector electronics through ultra-thin micro-structured silicon cooling plates is a very promising technique for pixel detectors in high energy physics experiments, especially at the LHC where the heavily irradiated sensors must be operated at temperatures below −20°C. It combines a very high thermal efficiency with a very low addition of mass and space, and suppresses all problems of CTE mismatch between the heat source and the heat sink. In addition, the use of CO2 as evaporative coolant liquid brings all the benefits of reliable and stable operation, but the high pressures involved impose additional challenges on the micro channel design and the fluidic connectivity. A series of designs have already been prototyped and tested for LHCb. The challenges, the current status of the measurements and the solutions under development will be described.

Research on Taylor Vortices in the Wedge-Shaped Air Gap of Evaporation Cooling Turbo Generator

Cooling technique is one of the most important parts to improve the development of turbo generator. Turbo generator with evaporative cooling stator and water cooling rotor possesses many excellent qualities for mid unit. In this system the stator bars and core are immerged in evaporative coolant, which could be cooled fully. The rotor bars are cooled by water inner cooling mode. In this paper, we describe the Taylor Vortices in the Wedge-shaped air gap of Evaporation cooling Turbo Generator and present the research on gas-flow and heat-transfer with different features in the turbo generator. The CFD method is used to analyze this system, which has different features, including gap size, rotating speed, Apex angle. And the heat-transfer calculation proves the axial direction gas-flow can do well to the rotator heat-emitting.

Safety and feasibility of nasopharyngeal evaporative cooling in the emergency department setting in survivors of cardiac arrest

Aim Mild therapeutic hypothermia improves survival and neurologic recovery in primary comatose survivors of cardiac arrest. Cooling effectivity, safety and feasibility of nasopharyngeal cooling with the RhinoChill device (BeneChill Inc., San Diego, USA) were determined for induction of therapeutic hypothermia. Methods Eleven emergency departments and intensive care units participated in this multi-centre, single-arm descriptive study. Eighty-four patients after successful resuscitation from cardiac arrest were cooled with nasopharyngeal delivery of an evaporative coolant for 1 h. Subsequently, temperature was controlled with systemic cooling at 33 °C. Cooling rates, adverse events and neurologic outcome at hospital discharge using cerebral performance categories (CPC; CPC 1 = normal to CPC 5 = dead) were documented. Temperatures are presented as median and the range from the first to the third quartile. Results Nasopharyngeal cooling for 1 h reduced tympanic temperature by median 2.3 (1.6; 3.0) °C, core temperature by 1.1 (0.7; 1.5) °C. Nasal discoloration occurred during the procedure in 10 (12%) patients, resolved in 9, and was persistent in 1 (1%). Epistaxis was observed in 2 (2%) patients. Periorbital gas emphysema occurred in 1 (1%) patient and resolved spontaneously. Thirty-four of 84 patients (40%) patients survived, 26/34 with favorable neurological outcome (CPC of 1–2) at discharge. Conclusions Nasopharyngeal evaporative cooling used for 1 h in primary cardiac arrest survivors is feasible and safe at flow rates of 40–50 L/min in a hospital setting.