A Novel Concept for Air Removal in Two-Phase Immersion Cooling Systems

A 10 kW scale model of a decoupled immersion cooling rig is constructed in order to serve as a testbed for immersion cooling, using 3M FC3284 dielectric cooling fluid. A species separator is constructed and demonstrates an ability to remove air from the flowfield before the condensable gases enter the condenser vessel, verified with Schlieren photography. The condenser underperformed significantly compared to initial sizing calculations using the NTU method, and film thickness of FC3284 liquid on the surface of the condenser was determined to be the cause due to low thermal conductivity of the liquid. The average film thickness on the surface of the condenser is calculated. In addition to the performance detriment of the film, air is also shown to reduce the condenser’s performance. The height of a transient stratification line is measured and compared against condenser power. Condenser efficacy losses are large and variable based on the concentration of air in the condenser vessel. A low vs high-mounted boiler is investigated. The mounting of the boiler has an effect on how much vapor is lost during a maintenance event. Finally, a comparison of the test rig’s overall cooling efficiency is made with various air-cooled datacenters by tracking energy consumption to cool a given IT load. This also translates to a reduction in carbon emissions.

Evaluation of Integral Effect of Thermal Comfort, Air Quality and Draught Risk for Desks Equipped with Personalized Ventilation Systems

This work evaluates the integral effect of thermal comfort (TC), indoor air quality (IAQ) and Draught Risk (DR) for desks with four personalized ventilation (PV) systems. The numerical study, for winter and summer thermal conditions, considers a virtual chamber, a desk, four different PV systems, four seats and four virtual manikins. Two different PV configurations, two upper and two lower air terminal devices (ATD) with different distance between them are considered. In this study a coupling of numerical methodology, using one differential and two integral models, is used. The heating, ventilating and air conditioning (HVAC) system performance in this work is evaluated using DR and room air removal effectiveness (εDR) that is incorporated in an Air Distribution Index (ADI). This new index, named the Air Distribution Turbulence Index (ADTI), is used to consider simultaneously the TC, the IAQ, the DR and the effectiveness for heat removal (εTC), contaminant removal (εAQ) and room air removal (εDR). The results show that the ADI and ADTI, are generally higher for Case II than for Case I, increase when the inlet air velocity increases, are higher when the exit air is located at a height 1.2 m than when is located at 1.8 m, and are higher for summer conditions than for winter conditions. However, the values are higher for the ADI than ADTI.

A solvent-free solid catalyst for the selective and color-indicating ambient-air removal of sulfur mustard

Bis(2-chloroethyl) sulfide or sulfur mustard (HD) is one of the highest-tonnage chemical warfare agents and one that is highly persistent in the environment. For decontamination, selective oxidation of HD to the substantially less toxic sulfoxide is crucial. We report here a solvent-free, solid, robust catalyst comprising hydrophobic salts of tribromide and nitrate, copper(II) nitrate hydrate, and a solid acid (NafionTM) for selective sulfoxidation using only ambient air at room temperature. This system rapidly removes HD as a neat liquid or a vapor. The mechanisms of these aerobic decontamination reactions are complex, and studies confirm reversible formation of a key intermediate, the bromosulfonium ion, and the role of Cu(II). The latter increases the rate four-fold by increasing the equilibrium concentration of bromosulfonium during turnover. Cu(II) also provides a colorimetric detection capability. Without HD, the solid is green, and with HD, it is brown. Bromine K-edge XANES and EXAFS studies confirm regeneration of tribromide under catalytic conditions. Diffuse reflectance infrared Fourier transform spectroscopy shows absorption of HD vapor and selective conversion to the desired sulfoxide, HDO, at the gas–solid interface.

Experimental researches of a two-level air-jet protection of an open surface of industrial baths of the big sizes

The developed two-level air-jet screen of an industrial bath is experimentally investigated. The principle of its operation is the supply of air by a shielding jet at the upper level and the suction of polluted air at the lower level symmetrically from opposite sides. At this stage of experimental research, the velocity fields and the nature of the interaction of inflow jets and suction flares have been studied. When determining the geometric dimensions of the air-jet screen structure, the location of key components and system elements, it is important to know, ensure and not exceed the allowable values of air flow velocity above the surface of the liquid mirror. During the observations of the aerodynamic properties of two-level air-jet screens, questions arose about the need to use flat rotational flows and control the velocity field in their interaction. Minimization of the interaction of inflow jets and flares of suction is the basis of the concept of designing a sсreen of this type. The shielding conditions have been experimentally confirmed due to the stabilization of the velocity field above the bath surface. The corresponding dependencies of change of formation of the protective air screen from the basic parameters as that a ratio of velocity "inflow-removal" and geometrical characteristics of a design are defined. For the developed air-jet screen of galvanic baths experimentally determined conditions of effective shielding are as follows: the ratio of the width of the slot for ejection of air from the working area to the width of the gas-tight wall is 0.75, and the ratio of screening jet velocity to air removal rate is within 0.3-2.45. This achieves a capture efficiency of up to 90 %. The expediency of arranging an ejection slot under the air supply slot to increase the flow rate and range of the jet has been confirmed.

Supramolecular interactions in the mixtures of hydrophobic and hydrophilic pyrogenic silicas

In order to study the peculiarities of the interaction of hydrophobic particles with water, the binding of water in composite systems based on structurally modified mixtures of 1/1 hydrophilic (A-300) and hydrophobic (AM-1-300) silica was studied by low-temperature 1H NMR spectroscopy. It is shown that with equal amounts of hydrophobic and hydrophilic components, the dependence of the interfacial energy on the value of surface hydration has a bell-shaped appearance with a maximum at h = 3000 mg/g. The obtained dependence is explained from the point of view of restructuring of the composite system under the influence of mechanical loads and the possibility of air removal and adsorption processes in the interparticle gaps of hydrophobic and hydrophilic components, as well as the phenomenon of nanocoagulation. Increasing the concentration of the hydrophilic component does not increase the binding energy of water. Under the influence of liquid hydrophobic substances, depending on the bulk density of the composite, there may be an increase or decrease in interfacial energy. The growth is due to the restructuring of the hydrophobic and hydrophilic components (nanocoagulation), and the decrease is due to the displacement of water from the surface into pores of larger radius. For n-decane, the effect of increasing the melting temperature by several tens of degrees was registered in the interparticle gaps.

Heat recovery by means of a ventilation unit

Energy consumption all over the world is constantly growing. To save energy, new technologies are being developed for the efficient use of energy resources. The goal of all new developments is to use less energy to provide the same level of energy supply for technological processes or buildings. The problem of energy saving is relevant for the ventilation system. Together with the removed air, a large amount of heat is lost, which is not advisable. In order to avoid these losses, heat recuperators began to be used, heating the cold supply air due to the warm air removed from the room. This development belongs to the field of energy saving. The goal is to increase efficiency by reheating the air after the heater with the help of a recuperator for a given temperature difference in the supply air before and after the recuperative heat exchanger. The development is a design of a ventilation unit with air removal and supply air ducts, combined into one housing with a separate, according to the “screw” principle, heat transfer wall, for use in the ventilation system in order to ensure an optimal microclimate in the room. Thus, as a result of using the presented device, the efficiency of the room ventilation unit is increased by reducing the energy consumption for heating the supply air with a heater.

Energy and Environment Analysis Methodology Application for the Study of the Clean Room Air Removal System in Microelectronics

The most part of chemical substances applied in clean rooms are aggressive and toxic, which requires analysis of air removal system not only from functionally related standpoint but also with regard to energy and environment. This study investigates the possibility of applying the methodology of energy and environmental analysis to compare the environmental friendliness of various air removal systems of clean rooms. It was shown that direct air removal, although having a thermodynamic advantage over a system with purification, was less favorable for the environment due to the significant level of the environmental index, which reflected the considerable potential economic damage from emissions to the atmosphere. This investigation has revealed the pollutants dominating in the composition of emissions and determining the validity of the decision on the structure of the air removal system of the clean room, taking into account the environmental, economic and biomedical aspects of its operation.

Design and optimization of oven vacuum bag (OVB) processing for void air removal in high-performance thermoplastic composites

Oven vacuum bag processing is an emerging process to manufacture high quality thermoplastic parts with void reduction using vacuum consolidation only. This paper models void air removal as a combination of through-the-thickness gas diffusion and in-plane airflow through the interlayer region for a flat plate of finite in-plane dimensions consisting of an arbitrary number of layers. A finite difference model assumes Fickian diffusion, simplifies the microstructure of the multi-layer prepreg stack and allows evaluation of various material and process conditions (inter- and intra-layer void content, temperature and pressure cycle, etc.) on the through-thickness diffusion behavior of the volatiles. In-plane airflow in the intra-layer is modeled using Darcy’s flow and requires high permeability of the interface created by the porous volume in between adjacent layers and the ability to vent the gas at the part edge. The dual mechanism model evaluates part geometries and processing cycles to reduce void content equivalent to autoclave parts with previously generated material properties of AS4/APC2 carbon PEEK prepreg. The modeling results based on the proposed mechanism shows that processing with through-the-thickness diffusion and standard processing cycles limits part thickness to five layers or less for APC2 while in-plane gas reduction can be used to make large parts of up to 10 m in the in-plane direction independent of part thickness. Very large parts require the addition of an intermediate lower temperature dwell cycle where diffusivity is high but interlayer permeability is unaffected allowing gas flow to the part edges for an extended period of time. The edge vent approach ensures a robust process even for as received materials with significant void variability often seen in thermoplastic prepreg tapes.

Mathematical Model of Air Pocket Evolution during Water Filling a Long-Slope Pipeline and Its Application to Air Removal Prediction

During water filling a long-slope pipeline, air pocket is very likely to be entrapped at peak point. In order to track air movement and predict air removal conditions, a mathematical model of air pocket evolution, including its formation, compression, and entrainment, is proposed in this paper. The simulation results were compared with the engineering field data and the two are basically consistent. Furthermore, the two most important factors which play a great role in the removal of air pocket, i.e., the terrain category and the inlet flow rate, are analyzed in detail. It is concluded that the removal conditions reach three outcomes: air pocket compressed and partly removed, compressed and completely removed, and compressed without any removal. In this paper, the terrain which leads to the last outcome is called the “Dangerous Terrain.” And for the “Dangerous Terrain,” it is of great importance that the inlet flow rate should be strictly confined within a certain level. While for the other two categories of terrains, an increased flow rate is in any respect beneficial to the removal of air pocket.