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2016

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Heat Transfer Analysis In The Cylinder Of Reciprocating Compressor, Ján Tuhovcák, Jí?Í Hej?Ík, Miroslav Jícha Jan 2016

Heat Transfer Analysis In The Cylinder Of Reciprocating Compressor, Ján Tuhovcák, Jí?Í Hej?Ík, Miroslav Jícha

International Compressor Engineering Conference

Heat transfer inside the cylinder of reciprocating compressor causes decrease of volumetric efficiency. The reason is superheating of the working fluid from the cylinder walls, which are heated up by the compression process itself. Decreasing gas superheating is favorable not just for efficiency, but also for reliability of a compressor. Understanding heat transfer phenomenon inside the cylinder is necessary step for that. Nowadays there are several empirical correlation available in the literature, which are often used in simulation tools due to their easy-to-use properties and capability of providing fast results with solid accuracy compared to more complex numerical models for …

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Application Of Single Blow Technique For Heat Transfer Measurement In Packed Bed Of Vegetables, Dariusz Butrymowicz, Adam Lapinski, Jerzy Gagan, Kamil Smierciew Jan 2016

Application Of Single Blow Technique For Heat Transfer Measurement In Packed Bed Of Vegetables, Dariusz Butrymowicz, Adam Lapinski, Jerzy Gagan, Kamil Smierciew

International Refrigeration and Air Conditioning Conference

The non-invasive measurement of the mean heat transfer coefficient for the packed bed of fruits and vegetables may be thought as still open issue. There is a clear need for the assessment of heat transfer conditions for various types of fruits and vegetables in order to accurately predict the thermal load that is necessary to select refrigeration equipment for cold storage chamber. Additionally, there is significant development in numerical modeling of heat and mass transfer processes in cold storage chambers for fruits and vegetables which requires precise heat transfer description. The theoretical basis for the indirect measurement approach of heat …

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Steady-State Numerical Simulation Of A Vapor Compression Heat Pump System As An Effective Method To Predict Its Performance, Zvonimir Jankovi?, Jaime Sieres Atienza, Fernando Cerdeira Pérez, Branimir Pavkovi? Jan 2016

Steady-State Numerical Simulation Of A Vapor Compression Heat Pump System As An Effective Method To Predict Its Performance, Zvonimir Jankovi?, Jaime Sieres Atienza, Fernando Cerdeira Pérez, Branimir Pavkovi?

International Refrigeration and Air Conditioning Conference

During the last two decades a strong driving force is directed to development of the simulation models and methodologies for vapor compression systems and its main components simulation. These models are highly useful as an effective method to predict the system performance and the thermodynamic processes of the vapor compression system under different operating conditions or different components’ properties. This paper presents the mathematical model of a reversible heat pump and numerical steady-state simulations with refrigerant R407C. Using the information from manufacturer data and real properties of scroll compressor, brazed plate heat exchangers and additionally built-in liquid-vapor heat exchanger, the …

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Density Of The Refrigerant Fluids Of R365mfc And R152a: Measurement And Prediction, Momin Elhadi Abdalla, Siddharth Pannir Jan 2016

Density Of The Refrigerant Fluids Of R365mfc And R152a: Measurement And Prediction, Momin Elhadi Abdalla, Siddharth Pannir

International Refrigeration and Air Conditioning Conference

This work presents the density of new environmentally friendly refrigerants 1,1-difluoroethane (R152a) and 1,1,1,3,3-Pentafluorbutane (R365mfc) in their pure fluid and mixture. The density is covered in the temperature range of -10-450C and the pressure range of p=0.65-10.47 bar. The density is measured by a vibrating-tube densitometer (DMA-HPM) manufactured by Anton Paar. The apparatus supplies data in the temperature range of -10°C to 200 °C and a pressure range of 0 to 1400 bar, with an uncertainty of 0.1%. The experimental data is validated using the ‘Volume Translated Peng Robinson Equation of State’ and high precision fundamental equations of state by …

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Refrigerant Circuit Optimization Of Dual-Mode Single-Row Microchannel Heat Exchangers Used For R410a Heat Pumps, Sunil Mehendale, Zhenning Li, Vikrant Aute Jan 2016

Refrigerant Circuit Optimization Of Dual-Mode Single-Row Microchannel Heat Exchangers Used For R410a Heat Pumps, Sunil Mehendale, Zhenning Li, Vikrant Aute

International Refrigeration and Air Conditioning Conference

Microchannel heat exchangers (MCHX) are being increasingly applied in heat pumps because of their compactness, significant charge reduction, lower refrigerant pressure drop and lower air-side fan power consumption compared to traditional round tube-plate fin (RTPF) heat exchangers. Using a microchannel condenser as well as evaporator in a heat pump system also offers significant potential for cost reduction. Very few studies on pass optimization of microchannel condensers and evaporators have appeared in the literature, and even fewer exist on the circuit optimization of dual-mode MCHX used in a heat pump. The influence of pass arrangement on the thermal-hydraulic performance of microchannel …

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Heat Transfer Of Condensation In Smooth Round Tube From Superheated Vapor, Jiange Xiao, Pega Hrnjak Jan 2016

Heat Transfer Of Condensation In Smooth Round Tube From Superheated Vapor, Jiange Xiao, Pega Hrnjak

International Refrigeration and Air Conditioning Conference

Heat transfer of R134a condensing in a horizontal smooth round tube with 6.1 mm inner diameter is invested in this study. Experimental results on the heat transfer coefficient (HTC) with mass flux from 50 to 200 kg m-2 s-1 and heat flux from 5 to 15 kW m-2 are provided. Heat transfer behavior is compared between condensing superheated (CSH) region and two-phase (TP) region. Experimental result shows that in TP region, higher mass flux results in higher HTC while heat flux does not affect HTC. In CSH region, however, mass flux does not affect HTC while HTC increases when heat …

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Optimal Heat Source Temperature For Supercritical Organic Rankine Cycle, Wei Liu, Christoph Wieland, Dominik Meinel, Hartmut Spliethoff Jan 2016

Optimal Heat Source Temperature For Supercritical Organic Rankine Cycle, Wei Liu, Christoph Wieland, Dominik Meinel, Hartmut Spliethoff

International Refrigeration and Air Conditioning Conference

Organic Rankine Cycle (ORC) enables power generation from low- to medium temperature heat sources. In an ORC, the organic medium shows different performances for different heat source temperatures. For a range of heat source temperatures, one temperature can be always identified corresponding to the best thermal match between the heat transfer fluid and working fluid. This temperature is defined as the Optimal Heat Source Temperature (OHST) and serves as an indicator for optimal efficiency. In this respect, the aim of this study is to investigate the OHST for supercritical fluid and its application in thermodynamic optimization. A simple ORC configuration …

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Preliminary Analysis Of A Fully Solid State Magnetocaloric Refrigeration, Mingkan Zhang, Ayyoub Mehdizadeh Momen, Omar Abdelaziz Jan 2016

Preliminary Analysis Of A Fully Solid State Magnetocaloric Refrigeration, Mingkan Zhang, Ayyoub Mehdizadeh Momen, Omar Abdelaziz

International Refrigeration and Air Conditioning Conference

Magnetocaloric refrigeration is an alternative refrigeration technology with significant potential energy savings compared to conventional vapor compression refrigeration technology. Most of the reported active magnetic regenerator (AMR) systems that operate based on the magnetocaloric effect use heat transfer fluid to exchange heat, which results in complicated mechanical subsystems and components such as rotating valves and hydraulic pumps. In this paper, we propose an alternative mechanism for heat transfer between the AMR and the heat source/sink. High-conductivity moving rods/sheets (e.g. copper, brass, iron or aluminum) are utilized instead of heat transfer fluid significantly enhancing the heat transfer rate hence cooling/heating capacity. …

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Experimental Performance Estimations Of Horizontal Ground Heat Exchangers For Gshp System, Md. Hasan Ali, Salsuwanda Bin Selamat, Keishi Kariya, Akio Miyara Jan 2016

Experimental Performance Estimations Of Horizontal Ground Heat Exchangers For Gshp System, Md. Hasan Ali, Salsuwanda Bin Selamat, Keishi Kariya, Akio Miyara

International Refrigeration and Air Conditioning Conference

Horizontal ground heat exchanger in ground source heat pump systems is susceptible to ground surface variations thus affecting its thermal performance. However, this configuration is desirable due to low installation costs as it mainly involved burying pipes in shallow trenches. In this study, the numerical simulation of thermal performance for slinky horizontal ground heat exchanger (GHE) loops in several operation modes is conducted in order to estimate the performance. This study also deals with experimental investigation of slinky type GHE buried in 1.5 m depth of the ground.

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Single Phase Pressure Drop And Flow Distribution In Brazed Plate Heat Exchangers, Wenzhe Li, Pega Hrnjak Jan 2016

Single Phase Pressure Drop And Flow Distribution In Brazed Plate Heat Exchangers, Wenzhe Li, Pega Hrnjak

International Refrigeration and Air Conditioning Conference

Brazed plate heat exchangers (BPHE) have been widely used in the heating, ventilating, air conditioning, and refrigeration industry, but refrigerant distribution among parallel plate channels is still one of the main issues. Maldistribution of refrigerant among different plate channels is greatly affected by the pressure changes along the inlet and outlet header, and it would generally decrease the performance of BPHE by causing higher pressure drop and poor utilization of heat transfer area. In this paper, the experimental and simulation methods are used to study the single-phase pressure drop and flow distribution in a U-type BPHE. Experiments are conducted to …

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Model-Based Optimal Control Of Variable Air Volume Terminal Box, Fuxin Niu, Zheng O'Neill, Xiaohui Zhou, Defeng Qian Jan 2016

Model-Based Optimal Control Of Variable Air Volume Terminal Box, Fuxin Niu, Zheng O'Neill, Xiaohui Zhou, Defeng Qian

International High Performance Buildings Conference

In the U.S. A Variable Air Volume (VAV) system is one of most commonly used air system for multiple-zone commercial buildings due to its capability to meet the varying heating and cooling loads of different building thermal zones. One of key component of VAV system is the terminal VAV box. There are an air damper and a reheat coil in the box. How to effectively and efficiently control the VAV box plays a significant role to reduce energy consumption and maintain acceptable indoor environment in buildings. Currently, there are two control logics used for controlling VAV box, namely, single maximum …

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A Non-Iterative Balancing Method For Hvac Duct System, Haoran Chen, Wenjian Cai, Qingguo Wang Jan 2016

A Non-Iterative Balancing Method For Hvac Duct System, Haoran Chen, Wenjian Cai, Qingguo Wang

International High Performance Buildings Conference

Building Heating, Ventilation and Air Conditioning (HVAC) system maintain comfortable indoor environment by supplying processed air to each terminal precisely through duct system. Testing, Adjusting and Balancing (TAB) plays critical role in achieving desired air distribution. Traditional TAB method is inaccurate and inefficient due to its trail-and-error natural, which forces people to pay high but expect low. Recently, it has been proposed that non-iterative approach to TAB is promising to improve performance and reduce cost. In this paper, a novel non-iterative balancing method is developed and implemented for TAB engineers to adjust dampers systematically and efficiently. Different from other TAB …

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Cfd Analysis Of Oil Flooded Twin Screw Compressors, Sham Ramchandra Rane, Ahmed Kovacevic, Nikola Stosic Jan 2016

Cfd Analysis Of Oil Flooded Twin Screw Compressors, Sham Ramchandra Rane, Ahmed Kovacevic, Nikola Stosic

International Compressor Engineering Conference

Modelling of screw compressors using Computational Fluid Dynamics (CFD) offers better insight into the working chamber of twin screw machines when compared with chamber models. As shown by authors in earlier publications, CFD models predict performance of dry gas and refrigeration compressors fairly accurately. However numerical flow models used for modelling of oil flooded twin screw compressors are still at the development stage. This is mainly due to the lack of understanding of the flow complexity and the techniques used for solving coupled equations that represent interactions between the gas and the oil in such machines. This paper presents the …

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An Investigation Into The Dynamics Of Self-Acting Compressor Valves, Carsten Möhl, Christiane Thomas, Ullrich Hesse Jan 2016

An Investigation Into The Dynamics Of Self-Acting Compressor Valves, Carsten Möhl, Christiane Thomas, Ullrich Hesse

International Compressor Engineering Conference

In principle, a reciprocating compressor stage consists of a cylinder, the working volume which varies periodically due to a piston moving inside a liner. Latter is sealed by two sets of valves. On the one hand the suction valve for admitting the gas to be compressed and on the other the discharge valve for allowing the high pressure gas to be delivered to the downstream process. The typical type of valves used within compressors for refrigeration plants are reed valves. The key feature of these mentioned valves - simultaneously affecting both their sealing performance as well as the reliability - …

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Experimental Investigation On The Operating Characteristics Of A Semi-Hermetic Twin Screw Refrigeration Compressor By Means Of P-V Diagram, Xiaokun Wu, Zhaorui Zhao, Wenqing Chen, Ziwen Xing Jan 2016

Experimental Investigation On The Operating Characteristics Of A Semi-Hermetic Twin Screw Refrigeration Compressor By Means Of P-V Diagram, Xiaokun Wu, Zhaorui Zhao, Wenqing Chen, Ziwen Xing

International Compressor Engineering Conference

In this paper, a comprehensive experimental investigation is carried out to evaluate the operating characteristics of a semi-hermetic twin screw refrigeration compressor at different oil flow rates and slide valve positions under various conditions. The working volume pressure of the compressor is recorded by a serial of sensors arranged in consecutive positions in the housing. These measured pressure data are then transformed into an indicator diagram. Based on the p-V diagrams, the effect mechanism of some factors such as evaporation temperature, condensation temperature, slide valve positions, oil flow rates for the suction and discharge end bearings lubricating and oil flow …

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A Modeling Study On The Operational Stability Of A Variable Speed Direct Expansion Air Conditioning System, Yudong Xia, Shiming Deng Jan 2016

A Modeling Study On The Operational Stability Of A Variable Speed Direct Expansion Air Conditioning System, Yudong Xia, Shiming Deng

International Refrigeration and Air Conditioning Conference

The instability in a refrigeration system, conventionally known as hunting, is the phenomena of the oscillation of certain system operational parameters such as the degree of refrigerant superheat (DS), refrigerant mass flow rate and evaporating pressure. Hunting has been noticed in not only the refrigeration systems controlled by thermostatic expansion valves (TEVs), but also those controlled by electronic expansion valves (EEVs), and hence attracted a lot of research interest. However, no previous studies on the impacts of both the operational parameters of an EEV and the simultaneous variation of compressor and supply fan speed in a variable speed (VS) direct …

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An Experimental Study On The Effect Of A New Defrosting Strategy On The Energy Consumption Of Household Refrigerators, Fernando Testoni Knabben, Claudio Melo Jan 2016

An Experimental Study On The Effect Of A New Defrosting Strategy On The Energy Consumption Of Household Refrigerators, Fernando Testoni Knabben, Claudio Melo

International Refrigeration and Air Conditioning Conference

In a previous study an experimental testing apparatus was constructed and used to measure the defrosting efficiency of different heaters working under different control strategies. Based on the results obtained two defrosting heaters (one calrod and one distributed) and two control strategies (constant power and steps mode) were selected for this study. In the original mode the power was held at 160 W for 17.0 and 19.3 min for the distributed and the calrod heaters, respectively. In the steps mode the power was gradually reduced from 160 to 20 W, and the defrost length was set to 28.5 and 22.3 …

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Research On The Performance Of A High Pressure 5.3mpa Twin Screw Compressor, Zhaorui Zhao, Xiaokun Wu, Feng Hou, Ziwen Xing Jan 2016

Research On The Performance Of A High Pressure 5.3mpa Twin Screw Compressor, Zhaorui Zhao, Xiaokun Wu, Feng Hou, Ziwen Xing

International Compressor Engineering Conference

High pressure twin screw compressors have been widely employed in fuel gas boosting and petrochemical industry. Recently, such compressors, whose maximum of discharging pressure is 5.3MPa, are also adopted in high temperature NH3 heat pumps and NH3/CO2 cascade refrigeration system. However, high pressure twin screw compressors are required to have large capacity, good performance and excellent stability at high operating pressure. In this paper, a semi-empirical model for open-type high pressure twin screw compressor is developed. Experimental research is conducted for identification of parameters, while validation is also made on the accuracy of the model. On the basis of theoretical …

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Theoretical And Experimental Analysis Of Scroll Expander, Bin Peng, Bingguo Zhu, Vincent Lemort Jan 2016

Theoretical And Experimental Analysis Of Scroll Expander, Bin Peng, Bingguo Zhu, Vincent Lemort

International Compressor Engineering Conference

In this article, both theoretical and experimental analysis on the performance of a new scroll expander will be presented and discussed. In order to investigate the performance of scroll expander, a detail mathematical modeling based on energy and mass balances is established. Radial and flank leakage, heat transfer between the working fluid, scroll wraps and plates, friction losses are considered in the mathematical modeling. Volume, temperature, pressure, mass flow of working chamber, friction loss power of moving parts, efficiency and power are investigated by solving the mathematical modeling. The experimental rig for scroll expander is set up. Results for various …

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Mechanistic Model Of An Oil-Flooded Single-Screw Expander, Davide Ziviani, Ian H. Bell, Michel De Paepe, Martijn Van Den Broek Jan 2016

Mechanistic Model Of An Oil-Flooded Single-Screw Expander, Davide Ziviani, Ian H. Bell, Michel De Paepe, Martijn Van Den Broek

International Compressor Engineering Conference

The power generated from Organic Rankine Cycles (ORCs) is directly related to the performance of the expander used, which in many cases it is adapted from the original compressor. The efficiency of positive displacement expanders depends on several aspects such as internal volume ratio and pressure ratio (under- and over-expansion), leakages, non-adiabatic expansion and heat losses to the ambient and mechanical losses. Thus, lubrication is often required to reduce friction and to seal leakage gaps. In this paper, the effect of oil-flooding on the performance of a single-screw expander is investigated. By varying the oil fraction, it is possible to …

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The Air Distribution Around Nozzles Based On Active Chilled Beam System, Bingjie Wu, Wenjian Cai, Qinguo Wang, Can Chen, Chen Lin, Haoran Chen Jan 2016

The Air Distribution Around Nozzles Based On Active Chilled Beam System, Bingjie Wu, Wenjian Cai, Qinguo Wang, Can Chen, Chen Lin, Haoran Chen

International High Performance Buildings Conference

During the past two decades, the utilization of Active Chilled Beam (ACB) systems as promising air-conditioning systems has becoming increasingly prevalent in Europe, North America and Asia. Due to the advantages of energy efficient, low acoustic effect and less space requirement, ACB systems are extensively applied in offices, laboratories and hospitals. However, the studies on air distribution uniformity of ACB systems are still inadequate. The air distribution has a great impact on thermal comfort. The un-uniformity of air distribution will easily lead to turbulent flow which can cause unpleased feeling such as draft in the occupied zone. ACB terminal unit …

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Current Based Hvac Systems Air Filter Diagnostics And Monitoring, Fadi M. Alsaleem, Michael Munroe, Mostafa Rafaie Rafaie Jan 2016

Current Based Hvac Systems Air Filter Diagnostics And Monitoring, Fadi M. Alsaleem, Michael Munroe, Mostafa Rafaie Rafaie

International High Performance Buildings Conference

This paper addresses the use of continuous indoor motor current to detect filter blockage in HVAC system. A commonly known phenomenon exists in the loading of a typical indoor motor blower that results in a power consumption decrease and hence less current draw for PSC motor, and power and currant draw increase for constant torque motor. Testing using Akaike information criterion (AIC), classification and regression tree (CART) models, and using both fixed radius basis function and linear basis function was described and performed against field of installed systems to determine if candidate data filter was sufficient, or to motivate use …

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A Volttron Based Implementation Of Supervisory Control Using Generalized Gossip For Building Energy Systems, Venkatesh Chinde, Adam Kohl, Zhanhong Jiang, Atul Kelkar, Soumik Sarkar Jan 2016

A Volttron Based Implementation Of Supervisory Control Using Generalized Gossip For Building Energy Systems, Venkatesh Chinde, Adam Kohl, Zhanhong Jiang, Atul Kelkar, Soumik Sarkar

International High Performance Buildings Conference

 Building energy systems comprising of many subsystems with local information and heterogenous preferences demand the need for coordination in order to perform optimally. The performance required by a typical airside HVAC system involving a large number of zones are multifaceted, involves attainment of various objectives (such as optimal supply air temperature) which requires coordination among zones. The use of traditional centralized optimization involving a large number of variables is very difficult to solve in near real time. This paper presents a novel distributed optimization framework to achieve energy efficiency in large-scale buildings. The primary goals are to achieve scalability, …

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Closed-Loop Scheduling For Cost Minimization In Hvac Central Plants, Michael J. Risbeck, Christos T. Maravelias, James B. Rawlings, Robert D. Turney Jan 2016

Closed-Loop Scheduling For Cost Minimization In Hvac Central Plants, Michael J. Risbeck, Christos T. Maravelias, James B. Rawlings, Robert D. Turney

International High Performance Buildings Conference

In this paper, we examine closed-loop operation of an HVAC central plant to demonstrate that closed-loop receding-horizon scheduling provides robustness to inaccurate forecasts, and that economic performance is not seriously impaired by shortened prediction horizons or inaccurate forecasts when feedback is employed. Using a general mixed-integer linear programming formulation for the scheduling problem, we show that optimization can be performed in real time. Furthermore, we demonstrate that closed-loop operation with a moderate prediction horizon is not significantly worse than a long-horizon implementation in the nominal case, and that closed-loop operation can correct for inaccurate long-term forecasts without significant cost increase. …

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Optimization Of Electricity Make/Buy Decisions For Purdue’S Wade Power Plant, Sugirdhalakshmi Ramaraj, James E. Braun, W. Travis Horton Jan 2016

Optimization Of Electricity Make/Buy Decisions For Purdue’S Wade Power Plant, Sugirdhalakshmi Ramaraj, James E. Braun, W. Travis Horton

International High Performance Buildings Conference

The Wade power plant at Purdue University produces chilled water, steam and electricity using CCHP (Combined Cooling, Heating and Power) systems to meet the campus cooling, heating and electricity demands. Steam generated from utility boilers is not only distributed through a steam tunnel system for campus heating but also used for power generation, chilled water production and in-plant auxiliary usage. Chilled water is generated using both steam driven chillers and electric chillers and is delivered through a closed water circulation loop to campus to meet the time-varying cooling demand. The electricity generated using two steam turbine driven generators provide 30-50% …

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A Multi-Agent Control Approach For Optimization Of Central Cooling Plants, Rita C. Jaramillo, James E. Braun, W. Travis Horton Jan 2016

A Multi-Agent Control Approach For Optimization Of Central Cooling Plants, Rita C. Jaramillo, James E. Braun, W. Travis Horton

International High Performance Buildings Conference

This paper presents an application of a multi-agent control approach for supervisory control of large central cooling plants. The starting point for this work was a multi-agent control simulation framework developed by Cai (2015).  To adapt the framework to the problem at hand several tasks were accomplished: agents representing the performance of the different devices of the plant were developed and inserted in the framework and generalized heuristics were incorporated to make the approach less computationally intensive. A case study of an existing cooling plant with significant complexity was utilized to conduct an extensive evaluation of the approach in …

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Solar Irradiance Modelling And Uncertainty On Building Hourly Profiles Of Heating And Cooling Energy Needs, Giovanni Pernigotto, Alessandro Prada, Paolo Baggio, Andrea Gasparella, Ardeshir Mahdavi Jan 2016

Solar Irradiance Modelling And Uncertainty On Building Hourly Profiles Of Heating And Cooling Energy Needs, Giovanni Pernigotto, Alessandro Prada, Paolo Baggio, Andrea Gasparella, Ardeshir Mahdavi

International High Performance Buildings Conference

Building energy simulations require a detailed characterization of the boundary conditions in order to solve the air heat balance problem. While for dry and dew bulb temperatures and wind speed, hourly profiles can be successfully developed from raw data measurements, to be included in weather files, beam and diffuse solar irradiance on the external surfaces of the building envelope are not directly known. Measured global solar irradiance is rarely available for the possible orientations of buildings surfaces and when the distinction between the beam and diffuse irradiance components is recorded, it is only for horizontal measurements. Consequently, solar irradiance models …

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Design And Application Of Distributed Economic Model Predictive Control For Large-Scale Building Temperature Regulation, Nishith R. Patel, James B. Rawlings, Michael J. Wenzel, Robert D. Turney Jan 2016

Design And Application Of Distributed Economic Model Predictive Control For Large-Scale Building Temperature Regulation, Nishith R. Patel, James B. Rawlings, Michael J. Wenzel, Robert D. Turney

International High Performance Buildings Conference

Although recent research has suggested model predictive control as a promising solution for minimizing energy costs of commercial buildings, advanced control systems have not been widely deployed in practice. Large-scale implementations, including industrial complexes and university campuses, may contain thousands of air handler units each serving a multiplicity of zones. A single centralized control system for these applications is not desirable. In this paper, we propose a distributed control system to economically optimize temperature regulation for large-scale commercial building applications. The decomposition strategy considers the complexities of thermal energy storage, zone interactions, and chiller plant equipment while remaining computationally tractable. …

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Numerical Modeling Of Capillary Compensated Aerostatic Bearing Applied To Linear Reciprocating Compressor, Emilio Rodrigues Hulse, Alvaro Toubes Prata Jan 2016

Numerical Modeling Of Capillary Compensated Aerostatic Bearing Applied To Linear Reciprocating Compressor, Emilio Rodrigues Hulse, Alvaro Toubes Prata

International Compressor Engineering Conference

Linear compressor uses a linear actuator to drive the piston directly in its reciprocating motion, eliminating several bearings that convert rotational into linear reciprocating motion, which is the common case in conventional reciprocating compressors. Â Additionally, the presence of side loads is minimized because the main forces in the mechanism are aligned to the axis of motion. Â Since the only sliding surface is the piston-cylinder interface, lubrication can be achieved using the refrigerant gas. Â In the present investigation, the equilibrium condition of capillary compensated gas lubricated piston for a linear compressor is fully explored. Â The main objective …

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Research On Injected Effect And Heat-Transfer Characteristics Of Narrow-Slit Injection Orifice Used For The Screw Compressor, Jia Xie, Jian Li, Kang Lian, Quanke Feng, Weifeng Wu Jan 2016

Research On Injected Effect And Heat-Transfer Characteristics Of Narrow-Slit Injection Orifice Used For The Screw Compressor, Jia Xie, Jian Li, Kang Lian, Quanke Feng, Weifeng Wu

International Compressor Engineering Conference

A narrow-slit injection orifice which is used for the screw compressor injection is described in this paper. Different from the traditional injection orifice, the orifice is slit shaped but not circular. Liquid which is injected by the narrow-slit injection orifice appears as a curtain shape so that the heat transfer area is increased. The cooling effect is enhanced and then the efficiency of the compressor is improved. The injected velocity of the orifice is simulated through the CFD software, and then the experiments are carried out. The study verified the accuracy of the simulation results. It will provide a theoretical …

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