Design of an adiabatic air conditioning package system

Air conditioning plays a significant role to maintain a cool atmosphere in warm conditions, However, the power consumed by the machine is higher. The commercial prevailing cooling systems are required to operate ventilation and cooling systems in buildings and in turn consumes more power. These systems apart from consuming electricity it also adds to the CO2 emissions to our environment. These energy consumption and CO2 emissions can be decreased by the assistance of energy effective frameworks to the prevailing air conditioning system. The study was conducted on a package unit of 414.2 kW by measuring the relative humidity, dry bulb, and wet bulb temperature to investigate the effect of indirect evaporative cooling on the systems COP. Also, the modelling of the package unit was done using Creo software and the analysis was carried out using ANSYS considering the flow and thermal analysis for different components of the package units. From this analysis it can be observed that by implementing the adiabatic cooling in package unit it is possible to save energy consumption. From the results it can be concluded that energy efficiency was more and the return on investment is high. Also, coefficient of performance of this machine is high and consumes less electricity and the expected energy savings is 20%.

HERA Phase I Limits on the Cosmic 21 cm Signal: Constraints on Astrophysics and Cosmology during the Epoch of Reionization

Recently, the Hydrogen Epoch of Reionization Array (HERA) has produced the experiment’s first upper limits on the power spectrum of 21 cm fluctuations at z ∼ 8 and 10. Here, we use several independent theoretical models to infer constraints on the intergalactic medium (IGM) and galaxies during the epoch of reionization from these limits. We find that the IGM must have been heated above the adiabatic-cooling threshold by z ∼ 8, independent of uncertainties about IGM ionization and the radio background. Combining HERA limits with complementary observations constrains the spin temperature of the z ∼ 8 neutral IGM to 27 K 〈 T ¯ S 〉 630 K (2.3 K 〈 T ¯ S 〉 640 K) at 68% (95%) confidence. They therefore also place a lower bound on X-ray heating, a previously unconstrained aspects of early galaxies. For example, if the cosmic microwave background dominates the z ∼ 8 radio background, the new HERA limits imply that the first galaxies produced X-rays more efficiently than local ones. The z ∼ 10 limits require even earlier heating if dark-matter interactions cool the hydrogen gas. If an extra radio background is produced by galaxies, we rule out (at 95% confidence) the combination of high radio and low X-ray luminosities of L r,ν /SFR > 4 × 1024 W Hz−1 M ⊙ − 1 yr and L X /SFR < 7.6 × 1039 erg s−1 M ⊙ − 1 yr. The new HERA upper limits neither support nor disfavor a cosmological interpretation of the recent Experiment to Detect the Global EOR Signature (EDGES) measurement. The framework described here provides a foundation for the interpretation of future HERA results.

SURFACE HEATER FABRICATION USING MICRO-LITHOGRAPHY FOR TRANSPIRATION COOLING HEAT TRANSFER COEFFICIENT MEASUREMENTS

Transpiration cooling is able to provide more uniform coolant coverage than film cooling to effectively protect the component surface from contacting the hot gas. Due to numerous coolant ejection outlets within a small area at the target surface, the experimental thermo-fluid investigation on transpiration cooing becomes a significant challenge. Two classic methods to investigate film cooling, the steady-state foil heater method and the transient thermography technique, both fail for transpiration cooling because the foil heater would block numerous coolant outlets, and the semi-infinite solid conduction model no longer holds for porous plates. In this study, a micro-lithography method to fabricate a silver coil pattern on top of the additively manufactured polymer porous media as the surface heater was proposed. The circuit was deliberately designed to cover the solid surface in a combination of series connection and parallel connection to ensure the power in each unit cell area at the target surface was identical. With uniform heat flux generation, the steady-state tests were conducted to obtain distributions of a pair of parameters, adiabatic cooling effectiveness, and heat transfer coefficient (HTC). The results showed that the adiabatic cooling effectiveness could reach 0.65 with a blowing ratio lower than 0.5. Meanwhile, the heat transfer coefficient ratio (hf/h0) of transpiration cooling was close to 1 with a small blowing ratio at 0.125. A higher HTC ratio was observed for smaller pitch-to-diameter cases due to more turbulence intensity generated at the target surface.

Discovery of a Wind-blown Bubble Associated with the Supernova Remnant G346.6-0.2: A Hint for the Origin of Recombining Plasma

We report on CO and H i studies of the mixed-morphology supernova remnant (SNR) G346.6−0.2. We find a wind-blown bubble along the radio continuum shell with an expansion velocity of ∼10 km s−1, which was likely formed by strong stellar winds from the high-mass progenitor of the SNR. The radial velocities of the CO/H i bubbles at V LSR = −82 to −59 km s−1 are also consistent with those of shock-excited 1720 MHz OH masers. The molecular cloud in the northeastern shell shows a high kinetic temperature of ∼60 K, suggesting that shock heating occurred. The H i absorption studies imply that G346.6−0.2 is located on the farside of the Galactic center from us, and the kinematic distance of the SNR is derived to be 11.1 − 0.3 + 0.5 kpc. We find that the CO line intensity has no specific correlation with the electron temperature of recombining plasma, implying that the recombining plasma in G346.6−0.2 was likely produced by adiabatic cooling. With our estimates of the interstellar proton density of 280 cm−3 and gamma-ray luminosity <5.8 × 1034 erg s−1, the total energy of accelerated cosmic rays of W p < 9.3 × 1047 erg is obtained. A comparison of the age–W p relation to other SNRs suggests that most of the accelerated cosmic rays in G346.6−0.2 have escaped from the SNR shell.

Investigating natural cooling of piled sugar beet

The paper examines the processes of natural cooling of a medium-storage pile containing 3,650 tons of sugar beets. Adiabatic cooling and related processes are established to have a predominant effect on reducing the temperature in the pile while in storage. Piled sugar beet is cooled due to some natural water evaporation from the surface of sugar beets, followed by moisture saturation of the outside air. Such cooling leads to an uncontrolled decrease in the quality of beets, which has negative implications during further processing. A formula is presented for calculating post-harvest yield loss in sugar beets piled with one slope being across the prevailing wind.

Photoplasmonic assembly of dielectric-metal, Nd2O3-Gold soret nanointerfaces for dequenching the luminophore emission

A variety of materials such as low dimensional carbon substrates (1D, 2D, and 3D), nanoprisms, nanocubes, proteins, ceramics, and DNA to name a few, have been explored in surface plasmon-coupled emission (SPCE) platform. While these offer new physicochemical insights, investigations have been limited to silver as primary plasmonic material. Although, gold nanoparticles (AuNPs) exhibit robust performance, its intrinsic property to quench the emission from radiating dipoles (at distances < 5 nm) has impeded its utility. Despite the use of metal-dielectric resonances (with Au decorated SiO2 NPs) and sharp nanotips (from Au nanostars) for dequenching the emission, the enhancements obtained has been less than 200-fold in SPCE platform. To address these long-standing challenges, we demonstrate the utility of gold soret colloids (AuSCs) and photonic crystal-coupled emission (PCCE) platform. The soret nano-assemblies synthesized using adiabatic cooling technique presented integrated hotspots when taken with high refractive index Nd2O3 ‘Huygens sources’. The collective and coherent coupling between localized Mie and delocalized Bragg plasmons (of sorets), dielectric plasmons (of Nd2O3), highly confined and intense Bloch surface waves (of PCCE platform) aided in realization of dequenched, as well as amplified > 1500-fold enhancements at the photoplasmonic nanocavity interface, presenting new opportunities for multidisciplinary applications.

Relationship of convection initiation and subsequent storm strength to ensemble simulated environmental conditions during IOP3b of VORTEX Southeast 2017

A fifty-member convection allowing ensemble was used to examine environmental factors influencing afternoon convection initiation (CI) and subsequent severe weather on 5 April 2017 during Intensive Observing Period (IOP) 3b of the Verification of Rotation in Tornadoes Experiment in the Southeast (VORTEX-SE). This case produced several weak tornadoes (rated EF1 or less), and numerous reports of significant hail (diameter ≥ 2 inches), ahead of an eastward-moving surface cold front over eastern Alabama and southern Tennessee. Both observed and simulated CI was facilitated by mesoscale lower-tropospheric ascent maximized several tens of km ahead of the cold-frontal position, and the simulated mesoscale ascent was linked to surface frontogenesis in the ensemble mean. Simulated maximum 2-5-km AGL updraft helicity (UHmax) was used as a proxy for severe-weather producing mesocyclones, and considerable variability in UHmax occurred among the ensemble members. Ensemble members with UHmax > 100 m2 s-2 had stronger mesoscale ascent than in members with UHmax < 75 m2 s-2, which facilitated more timely CI by producing greater adiabatic cooling and moisture increases above the PBL. After CI, storms in the larger UHmax members moved northeastward toward a mesoscale region with larger convective available potential energy (CAPE) than in smaller UHmax members. The CAPE differences among members was influenced by differences in location of an antecedent mesoscale convective system, which had a thermodynamically stabilizing influence on the environment toward which storms were moving. Despite providing good overall guidance, the model ensemble overpredicted severe weather likelihoods in northeastern Alabama, where comparisons with VORTEX-SE soundings revealed a positive CAPE bias.

Spectral index-flux relation for investigating the origins of steep decay in γ-ray bursts

Abstractγ-ray bursts (GRBs) are short-lived transients releasing a large amount of energy (1051 − 1053 erg) in the keV-MeV energy range. GRBs are thought to originate from internal dissipation of the energy carried by ultra-relativistic jets launched by the remnant of a massive star’s death or a compact binary coalescence. While thousands of GRBs have been observed over the last thirty years, we still have an incomplete understanding of where and how the radiation is generated in the jet. Here we show a relation between the spectral index and the flux found by investigating the X-ray tails of bright GRB pulses via time-resolved spectral analysis. This relation is incompatible with the long standing scenario which invokes the delayed arrival of photons from high-latitude parts of the jet. While the alternative scenarios cannot be firmly excluded, the adiabatic cooling of the emitting particles is the most plausible explanation for the discovered relation, suggesting a proton-synchrotron origin of the GRB emission.

Surface Heater Fabrication Using Micro-Lithography for Transpiration Cooling Heat Transfer Coefficient Measurements

Transpiration cooling is able to provide more uniform coolant coverage than film cooling to effectively protect the component surface from contacting the hot gas. Due to numerous coolant ejection outlets within a small area at the target surface, the experimental thermo-fluid investigation on transpiration cooing becomes a significant challenge. Two classic methods to investigate film cooling, the steady-state foil heater method and the transient thermography technique, both fail for transpiration cooling because the foil heater would block numerous coolant outlets, and the semi-infinite solid conduction model no longer holds for porous plates. In this study, a micro-lithography method to fabricate a silver coil pattern on top of the additively manufactured polymer porous media as the surface heater was proposed. The circuit was deliberately designed to cover the solid surface in a combination of series connection and parallel connection to ensure the power in each unit cell area at the target surface was identical. With uniform heat flux generation, the steady-state tests were conducted to obtain distributions of a pair of parameters, adiabatic cooling effectiveness, and heat transfer coefficient (HTC). The results showed that the adiabatic cooling effectiveness could reach 0.65 with a blowing ratio lower than 0.5. Meanwhile, the heat transfer coefficient ratio (hf/h0) of transpiration cooling was close to 1 with a small blowing ratio at 0.125. A higher HTC ratio was observed for smaller pitch-to-diameter cases due to more turbulence intensity generated at the target surface.

ANALYSIS OF THE ENERGY, ECONOMIC AND ENVIRONMENTAL EFFICIENCY OF AIR CONDITIONING SYSTEMS WITH DIRECT AND INDIRECT EVAPORATIVE COOLING

The article is devoted to the analysis of energy, economic and environmental efficiency, which are achieved by using indirect adiabatic cooling of air in the central air conditioner instead of direct cooling. Two corresponding schematic diagrams of air conditioning systems are considered. As a result of the calculations, it was found that indirect adiabatic cooling of the air makes it possible to reduce the consumption of cold and electricity by 65%. The monetary equivalent of reducing energy consumption can reach UAH 14,760 for 4 months of operation of the air conditioning system in cooling mode. Also, the use of this mode of operation of climatic equipment makes it possible to obtain a certain environmental effect in the form of reducing carbon dioxide emissions at the level of 5.15 tons per season.Keywords: indirect evaporative cooling, refrigeration capacity, irrigation chamber, economic efficiency, ecological effect