Experimental Study of a Novel Shape-Optimized Air-to-Refrigerant Heat Exchanger under Evaporator Conditions

Air-conditioning, heating, and refrigeration systems account for a significant fraction of the primary energy consumption in many parts of the world and have a direct impact on our quality of life. Air-to-refrigerant heat exchangers are a key component in these systems. Their airside thermal resistance is dominant and accounts for more than 80% of the overall resistance. Reducing the airside thermal resistance to improve the thermal-hydraulic performance of these heat exchangers, and consequently overall system level COP, has been a topic of research focus for several decades. Generally, secondary surfaces, i.e., fins, are used to enhance the airside performance by drastically increasing surface area. However, fins have disadvantages such as, increased material usage, reduced compactness, and increased viscous resistance. Therefore, it is evident air-to-refrigerant heat exchanger designs have the potential for improved thermal-hydraulic performance by avoiding the use of fins and utilizing different designs. Computational Fluid Dynamics and Multi-Objective Genetic Algorithms were used to design heat exchangers with novel and topology optimized tube shapes. This paper presents an experimental study of a 1-2 kW prototype air-to-refrigerant heat exchanger based on one such optimized tube shape, termed “Copper NURBS Tube Heat Exchanger-1” (CNTHX1). The heat exchanger was manufactured using conventional manufacturing methods. When compared to a state-ofthe-art air-to-refrigerant heat exchanger, the prototype is designed to have a 25% reduction in volume, 20% reduction in face area, and 8% reduction of internal volume with equal to or greater capacity and the same airside pressure drop. This work presents the experimental performance of this prototype under wet and dry evaporator (R410A) conditions in a standardized wind-tunnel. Experimental airside pressure drop and capacity were measured and compared to predicted values. Additionally, the energy balance between the airside and refrigerant-side was within ±5.5% for all test points. The detailed thermal-hydraulic characteristics and the reasons for improvement are discussed

Magnetic Lensing near Ultramagnetized Neutron Stars

Extremely strong magnetic fields change the vacuum index of refraction. This induces a lensing effect that is not unlike the lensing phenomenon in strong gravitational fields. The main difference between the two is the polarization dependency of the magnetic lensing, a behaviour that induces a handful of interesting effects. The main prediction is that the thermal emission of neutron stars with extremely strong magnetic fields is polarized - up to a few percent for the largest fields known. This potentially allows a direct method for measuring their magnetic fields.Comment: To appear in MNRAS, 12 pages, 9 figure

Management of intra-abdominal infections : recommendations by the WSES 2016 consensus conference

This paper reports on the consensus conference on the management of intra-abdominal infections (IAIs) which was held on July 23, 2016, in Dublin, Ireland, as a part of the annual World Society of Emergency Surgery (WSES) meeting. This document covers all aspects of the management of IAIs. The Grading of Recommendations Assessment, Development and Evaluation recommendation is used, and this document represents the executive summary of the consensus conference findings.Peer reviewe

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

Design and baseline characteristics of the finerenone in reducing cardiovascular mortality and morbidity in diabetic kidney disease trial

Background: Among people with diabetes, those with kidney disease have exceptionally high rates of cardiovascular (CV) morbidity and mortality and progression of their underlying kidney disease. Finerenone is a novel, nonsteroidal, selective mineralocorticoid receptor antagonist that has shown to reduce albuminuria in type 2 diabetes (T2D) patients with chronic kidney disease (CKD) while revealing only a low risk of hyperkalemia. However, the effect of finerenone on CV and renal outcomes has not yet been investigated in long-term trials. Patients and Methods: The Finerenone in Reducing CV Mortality and Morbidity in Diabetic Kidney Disease (FIGARO-DKD) trial aims to assess the efficacy and safety of finerenone compared to placebo at reducing clinically important CV and renal outcomes in T2D patients with CKD. FIGARO-DKD is a randomized, double-blind, placebo-controlled, parallel-group, event-driven trial running in 47 countries with an expected duration of approximately 6 years. FIGARO-DKD randomized 7,437 patients with an estimated glomerular filtration rate >= 25 mL/min/1.73 m(2) and albuminuria (urinary albumin-to-creatinine ratio >= 30 to <= 5,000 mg/g). The study has at least 90% power to detect a 20% reduction in the risk of the primary outcome (overall two-sided significance level alpha = 0.05), the composite of time to first occurrence of CV death, nonfatal myocardial infarction, nonfatal stroke, or hospitalization for heart failure. Conclusions: FIGARO-DKD will determine whether an optimally treated cohort of T2D patients with CKD at high risk of CV and renal events will experience cardiorenal benefits with the addition of finerenone to their treatment regimen. Trial Registration: EudraCT number: 2015-000950-39; ClinicalTrials.gov identifier: NCT02545049