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"On The Dynamics Of A Three Stage Single Acting Reciprocating Compressor", Sinan "Pişirici", Eren "Çakır", Haluk "Erol"

International Compressor Engineering Conference

The growing demand in the market for highly efficient, more reliable and less expensive compressors have activated the manufacturers to develop state-of-the-art analytical tools to predict, evaluate and optimize the existing as well as creating the new designs. Development of a mathematical tool for predicting the dynamic behavior saves considerable time and reduces the unnecessary number of prototypes as well as the development costs. In the present study, a non-linear dynamic model of a three stage single acting reciprocating compressor is developed to predict the entire motion of the compressor. The analytical model prepared for simulation of the motion is …

Performance Analysis On A Variable Capacity Swash Plate Compressor, Jae Woong Choi, Jeong Taek Lim, Young Jae Noh, Hyun-Jin Kim, Pil Gon Song, Seong-Min Pae

International Compressor Engineering Conference

A numerical study on the performance of a variable capacity swash plate compressor for an automotive air-conditioning system was carried out. The compressor under investigation had six cylinders and capacity regulation was made by changing the swash plate inclination angle. A numerical simulation program was made based on mathematical modelings on the swash plate dynamics, refrigerant states in various control volumes such as cylinders and crank room, and flows in the opening passages of electric control valve for crank room pressure control. The simulation results such as mass flow rate, compressor power consumption, cooling capacity and COP were compared with …

Improving The Reliability Of A Domestic Refrigerator Compressor Subjected To Repetitive Loading, Seongwoo Woo, Dennis O'Neal

International Compressor Engineering Conference

As a reliability quantitative specification, parametric accelerated life testing was used to assess the reliability of a newly designed compressor of a commercial refrigerator subjected to repetitive stresses. A generalized life-stress failure model and new sample size equation with a new load concept were derived starting with the basic refrigeration cycle. The sample size equation with the acceleration factor also enabled the parametric accelerated life testing to quickly evaluate the expected lifetime. The design of this testing should help an engineer uncover the design parameters affecting reliability during the design process of the compressor system. Consequently, it should help companies …

A Longitudinal Analysis On The Feasibility Of Iris Recognition Performance For Infants 0-2 Years Old, Torrey Hutchison

Purdue Polytechnic Masters Theses

The focus of this study was to longitudinally evaluate iris recognition for infants between the ages of 0 to 2 years old. Image quality metrics of infant and adult irises acquired on the same iris camera were compared. Matching performance was evaluated for four groups, infants 0 to 6 months, 7 to 12 months, 13 to 24 months, and adults. A mixed linear regression model was used to determine if infants’ genuine similarity scores changed over time. This study found that image quality metrics were different between infants and adults but in the older group, (13 to 24 months old) …

Stem Educators: Who Are They?, Anne M. Lucietto, Liza Ann Russell

School of Engineering Technology Faculty Publications

Technical education or STEM (Science, Technology, Engineering, and Mathematics) education is often touted as the way for students to succeed, for corporations to move forward, and to gain prominence in the world economy. With all this promotion, do we know who is teaching these subjects to our students? This question urged researchers to develop a survey and distribute it to those teaching STEM subjects. The survey collected a variety of information, the results of the demographic section being reported here. The survey responses are from a population of STEM educators teaching at all levels, found to be male and generally …

Development And Impact Of Teacher Social Capital In An Engineering Education Teacher Professional Development Program, Wei Zakharov

Libraries Faculty and Staff Scholarship and Research

Teacher social capital is a set of social interaction assets such as collegiality and collaboration that enable teachers to work with each other in groups to improve teaching and learning. This results in instructional improvement and student success in school reform.

This study discusses how an engineering education teacher professional development program has developed an environment for long-term collegiality and collaboration among its teachers. Furthermore, the study presents an empirical evidence of the impact of teacher social capital on students’ engineering knowledge learning.

Ninety teachers and 621 students are examined in this program. The participants are from fifteen elementary schools …

Informed Learning Design: Teaching And Learning Through Engagement With Information, Clarence Maybee, Christine Susan Bruce, Mandy Lupton, Ming Fai Pang

Libraries Faculty and Staff Scholarship and Research

While higher education teachers are able to use information in sophisticated ways to learn and communicate within their disciplines, they may not be accustomed to teaching their students to use information creatively and reflectively to support their work in a course. This paper introduces informed learning design, a curriculum design model by which teachers specifically enable students to learn course content through intentionally design engagement with information. Drawing from informed learning pedagogy and the variation theory of learning, the design model outlines an instructional pattern for enabling student awareness of critical aspects and features of the object being studied related …

Design And Testing Of A Microchannel Heat Exchanger Working As Condenser And Evaporator, Emanuele Zanetti, Marco Azzolin, Stefano Bortolin, Giulio Busato, Davide Del Col

International Refrigeration and Air Conditioning Conference

In the recent years, international agreements and regulations urge for a reduction of production and utilization of Hydrofluorocarbons (HFCs), while achieving high efficiency remains a crucial aspect for refrigeration and air conditioning systems. One of the possible candidates to replace the high global warming potential (GWP) fluid currently employed in heat pump systems (R410A) is the refrigerant R32, which belongs to A2L class. In addition to adopting low-GWP refrigerants, charge minimization is a major design objective for such systems, mainly in the case of flammable refrigerants. In the case of reversible heat pumps, a reduced volume of the heat exchangers …

Steady-State Modeling Of Condensing Units With An Economizer Loop, Haithem Murgham, David Myszka, Vijay Bahel, Nathan Burns, Kyaw Wynn, Mike Saunders, Rajan Rajendran

International Refrigeration and Air Conditioning Conference

This paper presents an engineering model that simulates the steady-state operation of air-cooled condensing units. Packaged, air-cooled, condensing units includes a compressor, condensing coil, tubing, and fans, fastened to a base or installed within an enclosure. To increase capacity, modern condensing units are being equipped with a brazed-plate heat exchanger for an economizer loop, configured in either upstream or downstream extraction schemes.

Thermoeconomic Diagnosis Of Air Conditioning Systems: Experimental Assessment Of Performance And New Developments For Improved Reliability, Pietro Catrini, James E. Braun, Antonio Piacentino, Andrew L. Hjortland, Akash Patil

International Refrigeration and Air Conditioning Conference

In the last two decades, great progress has been made in improving the efficiency of air-conditioning equipment. In addition to improved performance of new equipment, there has been an increasing interest in technologies that can maintain performance over time. This has led to research and development of Fault Detection and Diagnosis (FDD) techniques for air conditioning systems, that can support building owners in scheduling cost-effective maintenance and repairs. Among FDD techniques, thermoeconomic diagnosis is a novel method for the identification of faults occurring in air conditioning systems. A very limited number of papers have focused on this topic, and the …

Heat Transfer Enhancement Using Approximation Assisted Optimization For Pillow Plate Heat Exchangers, Radia Eldeeb, Jiazhen Ling, Vikrant Chandramohan Aute, Reinhard Radermacher

International Refrigeration and Air Conditioning Conference

Optimization is a powerful mathematical methodology that can be employed to miniaturize and improve the performance of plate heat exchangers in order to achieve higher levels of energy efficiency. Achieving these goals means less material used, and less charge, and thus a lower impact on the environment Plate heat exchangers (PHXs) are favored by the HVAC&R industry since they combine between the advantages of compactness, and desirable thermal-hydraulic characteristics due to their small approach temperature. However, the challenge with plate heat exchangers lies within the costly new designs. Pillow plate heat exchanger (PPHX) is a promising type of PHXs which …

Defrosting Performance Of Patterned Heat Transfer Surfaces With A Superhydrophobic Silica Nanosprings Coating, Nickolas C. Schmiesing, Griffin Barrington, Giancarlo Corti, Andrew Sommers

International Refrigeration and Air Conditioning Conference

The overall aim of this work was to study the defrosting performance of functionalized heat transfer surfaces containing a novel, silica nanosprings coating combined with preferential microstructural roughness. In doing this, differences in drainage rates and defrosting effectiveness were explored both on patterned and non-patterned surfaces. To date, ten different surfaces have been examined— an uncoated, untreated aluminum plate (S1), plates containing a silica nanospring (SN) coating of varying thickness (S2-S6), a plate containing evenly-spaced microchannels both with and without the SN surface coating (S7, S8), and then finally a plate containing a microstructural roughness gradient both with and without …

Thermal-Hydraulic Optimization Of Fan-Supplied Tube-Fin Evaporators For Frosting Conditions Aiming At Minimum Energy Consumption, Rafael Ribeiro, Christian Hermes, Diogo Lôndero Da Silva

International Refrigeration and Air Conditioning Conference

This work is aimed at the optimal design (i.e. number of transversal and longitudinal tube rows, number of fins) of fan-supplied tube-fin evaporators for light commercial refrigeration applications operating under frosting conditions. Quasi-steady-state algebraic models were put forward for the refrigeration cycle and its components for computing not only the cooling capacity depletion due to the evaporator frosting over time, but also the changes experienced by the evaporating temperature and its effect on the compressor power. Transient, unsteady-state algebraic models were also advanced to account for the temperature and humidity variations inside the refrigerated compartment, and so the compressor runtime. …

Defrost Cycle Optimization For Fan-Supplied Tube-Fin Evaporators Subjected To Frosting Conditions, Diogo Lôndero Da Silva, Christian Hermes

International Refrigeration and Air Conditioning Conference

Frost accretion on a tube-fin evaporator surface raises its thermal and hydraulic resistances, which in turn deteriorates the cooling capacity of the refrigeration system. For this reason, periodic defrost operations are required to recover the initial performance of the system. Most defrost techniques rely on supplying heat to the frost layer. Due to technological and thermodynamic limitations, only part of the heat supply is effectively used to melt the frost built-up on the evaporator, while the rest increases the refrigerator thermal load. Therefore, the amount of heat dissipated, the duration of a defrost operation, and the time between two consecutives …

An Experimentally Validated Model Of Single-Phase Flow Distribution In Brazed Plate Heat Exchangers, Wenzhe Li, Predrag S. Hrnjak

International Refrigeration and Air Conditioning Conference

This paper presents a mathematical model to predict single-phase flow distribution in brazed plate heat exchangers (BPHEs). In this model, the flow distribution among parallel channels is predicted by imposing the condition that each flow path in the heat exchanger has an identical total pressure drop. The model has been validated by the experiments, in which the pressure drop of gas flow in the headers, as well as across the channels is measured. This model is then used to explore the effect of maldistribution on the thermal performance of the heat exchangers. The experimental and modeling results show that, for …

An Experimental Study Of Hc-600a Flow Through Variable Expansion Devices For Household Refrigerators, Fernando Testoni Knabben, Joel Boeng

International Refrigeration and Air Conditioning Conference

This work focuses on the HC-600a flow through small capacity fixed and variable expansion devices. To this end three electronic expansion valves of the same innovative design but with distinct orifices, were firstly tested in a dry nitrogen flow testing apparatus by varying the opening ratio an the operating conditions. Secondly, equivalent capillary tubes were defined based on the measured nitrogen mass flow rates through an updated version of the well know Kipp Schmidt’s equation. Thirdly, simulations were carried out with an in-house validated capillary tube model to estimate the HC-600a mass flow rate, using the length and inner diameter …

Theoretical And Experimental Investigations On The Recirculation Of The Solution (Mix-Flow) In An Absorption Resorption Refrigeration System, Oliver Ziegler, Ullrich Hesse

International Refrigeration and Air Conditioning Conference

Ammonia water absorption resorption refrigeration systems do not need a rectification column like conventional absorption refrigeration systems do. In this case such systems need a recirculation of the solution. This so called “mix flow” is necessary to prevent the dilution of the solution in the “cold cycle” of the system which is caused by the relative high concentration of water in the hot vapor. The influence of this recirculation of the solution on the performance of the system could be shown in previous studies and is now modelled and investigated more in detail. As a result of the theoretical investigation, …

Dynamic Performance Of A Mechanical Vapor Compression (Mvc) Desalination System, Sergio Morales Ruiz, Jesús Castro, Joaquim Rigola, Carles Oliet, Assensi Oliva

International Refrigeration and Air Conditioning Conference

This paper presents a numerical model to analyze the thermal and fluid dynamic behavior of a mechanical vapour compression MVC desalination system. The MVC desalination method is an evaporation and condensation process that occurs at low pressure, which requires a compression work to increase the saturation temperature of the vapor. The compressed vapor is condensed and its latent heat is transferred to the feed seawater. The MVC desalination is used at low and medium scale in comparison with other techniques such as: multistage flash desalination (MSF) or reverse osmosis (RO). The MVC desalination unit studied in this paper uses renewable …

A Literature Review Of Numerical Modeling Techniques For Vapor Compression Systems With Focus On Heat Exchanger Modeling, Omer Sarfraz, Christian K. Bach, Craig Bradshaw

International Refrigeration and Air Conditioning Conference

Vapor compression systems are the most widely used system type in heating, ventilation, air-conditioning, and refrigeration (HVAC&R) applications. Experimental and numerical modeling techniques are used to analyze the performance of the vapor compression systems. With the introduction of high-performance computers, numerical modeling techniques are used extensively to develop cost-effective and efficient HVAC&R equipment. Experimental iterations on the design of vapor compression systems are costly; however, numerical techniques can reduce the number of experimental iterations, substantially decreasing the development cost and time. Because of the benefits associated with the numerical simulation, many researchers working in the HVAC&R field have attempted to …

Atg Interviews Gary Marchionini, Dean, School Of Information And Library Science, University Of North Carolina, Chapel Hill, Katina Strauch, Tom Gilson

Against the Grain

No abstract provided.

Thermo-Hydraulic Model For Steam Condensation In A Large, Inclined, Flattened-Tube Air-Cooled Condenser, William A. Davies, Predrag S. Hrnjak

International Refrigeration and Air Conditioning Conference

A thermo-hydraulic model for calculating capacity, heat transfer coefficient and void fraction of an inclined air-cooled steam condenser is presented. The condenser tube has an elongated-slot cross-section, with inner dimensions of 214 x 16 mm. The tube is 10.7 m long. The model is for downward inclination angles from 0-90o, with co-current vapor and condensate flow. The cooling air is in cross flow. This model is developed based on existing models for inclined, stratified-flow condensation models. These have been adapted to the current geometry and conditions for the development of the current model. The model couples both air- and steam-side …

Comparison Of Approximation-Assisted Component Modeling Methods For Steady State Vapor Compression System Simulation, Ransisi Huang, Jiazhen Ling, Vikrant Chandramohan Aute

International Refrigeration and Air Conditioning Conference

An accurate, fast and robust heat exchanger model is critical for reliable steady state simulation of vapor compression systems. In such simulations, the heat exchanger models are often the most time consuming components and can be plagued by severe non-linearities especially if they are black-box or third-party provided. This paper investigates and compares different approaches for heat exchanger performance approximation, with the distributed parameter approach being the baseline. The methods are: Gaussian kernel based on Kriging, a multi-zone approach, and polynomial regression. Generally, distributed parameter models have the highest level of accuracy but can be time-consuming. Kriging metamodels have relatively …

Online Measurement Of The Working Fluid Mass Repartition In A Small-Scale Organic Rankine Cycle Power System, Rémi Dickes, Olivier Dumont, Sylvain Quoilin, Vincent Lemort

International Refrigeration and Air Conditioning Conference

This paper presents an experimental investigation of the working fluid charge repartition in a 2kWe ORC (organic Rankine cycle) test bench. To this end, an online measurement apparatus is built and fully calibrated to evaluate the charge enclosed in the three heat exchangers and the liquid receiver of the ORC unit. By changing all the system boundary conditions (including the charge enclosed in the test rig), an experimental database of 304 steady-state points is gathered and post-treated. The charge inventories obtained by online measurements demonstrate promising results on average but experience high uncertainties when considering each point individually (i.e. the …

Little Red Herrings — #Deletefacebook?, Mark Y. Herring

Against the Grain

No abstract provided.

Op Ed-Epistemology — A Matter Of Trust, Scott T. Plutchak

Against the Grain

No abstract provided.

Atg Interviews Joris Van Rossum, Director Of Special Projects, Digital Science, Katina Strauch, Tom Gilson

Against the Grain

No abstract provided.

One Monographs Bucket, Kelly Smith

Against the Grain

No abstract provided.

Mayflower: Ode To New Beginnings — Distinction For The Library Profession: Taking A Page From The Business Playbook, Antje Mays

Against the Grain

No abstract provided.

Textbooks On Reserve — Seven Years And Going Strong, Becky Demartini, Marynelle Chew, Michael Aldrich

Against the Grain

No abstract provided.

Considering Games And Gamification In Libraries & Associated Entities — In Praise Of Real People, Jared Alexander Seay

Against the Grain

No abstract provided.