The document describes an experiment to determine the volumetric efficiency of an air compressor at different speeds and pressures. It provides background on compressors and defines volumetric efficiency. The procedures, calculations, results and analysis are presented. Key findings include that volumetric efficiency varies with load and speed, is reduced from theoretical by clearance volume, and is affected by factors like induction/exhaust friction. Suggestions to minimize errors in the experiment are also provided.
Theoretical cycle based on the actual properties of the cylinder contents is called the fuel air cycle.
The fuel air cycle takes into consideration the following.
The ACTUAL COMPOSITION of the cylinder contents.
The VARIATION OF SPECIFIC HEAT of the gases in the cylinder.
The DISSOCIATION EFFECT.
The VARIATION IN THE NUMBER OF MOLES present in the cylinder as the pressure and temperature change
in this presentation , the different engine inefficiencies has been discussed including all sort of friction losses which affects the brake power of the engine. It includes volumetric efficiency, thermal efficiency, IMEP, BMEP, brake power etc.
Theoretical cycle based on the actual properties of the cylinder contents is called the fuel air cycle.
The fuel air cycle takes into consideration the following.
The ACTUAL COMPOSITION of the cylinder contents.
The VARIATION OF SPECIFIC HEAT of the gases in the cylinder.
The DISSOCIATION EFFECT.
The VARIATION IN THE NUMBER OF MOLES present in the cylinder as the pressure and temperature change
in this presentation , the different engine inefficiencies has been discussed including all sort of friction losses which affects the brake power of the engine. It includes volumetric efficiency, thermal efficiency, IMEP, BMEP, brake power etc.
Air compression systems with hydraulic dynamic energyeSAT Journals
Abstract A compressor is a machine that capable of compressing and delivering the air at a desired pressure value. It is driven with a prime mover. Air compressor takes in atmospheric air, compresses and delivers to a storage tank. There are many principles of compressors up to now, here we are introduced another principle of air compression system with hydraulic dynamic energy which may be used alternative to all compressors because of its advantages. In order to satisfy these new responsibilities, maintenance, operations, and engineering personnel need continuous review of compressor types, classifications, and applications. HACS overcomes disadvantages of reciprocating compressor for the same pressure produced, like vibrations, discharge air temperature, lubrication and noise. In HACS crank mechanism is eliminated and diving force for the motion of piston is done by pumping the incompressible liquid into the cylinder. Keywords: Compressor, Dynamic energy, HACS, Machine and Piston.
Compressor Types
Compressor Performance
Compressed Air System Components
Efficient Operation of Compressed Air Systems
Compressor Capacity Assessment
Checklist for Energy Efficiency in Compressed Air System
00923006902338
Types of air compressors, Compressor efficiency, Efficient compressor
operation, Compressed air system components, Capacity assessment, Leakage test,
Factors affecting the performance and efficiency
"Capture" in a lambda expression - C++
A lambda expression is an anonymous, inline function. It is used to create a local function, mainly for passing as an argument to a function call or as a return value.
"Capture" makes variables in the local scope available for use in the body of the lambda expression. By default, variables are captured by value. Variables can be captured by the reference as well. Also, there are syntaxes which allow passing all the local variables and objects into the lambda expression.
What is CAD? What is CAE? and What is CAM? Did you hear about those three terms before? If so, what is the dedicated software, and how do they differ?
The first two letters of each word, "CA" stands for "Computer Aided", which means all three systems are created to help the user to achieve their goals with the power of computers.
In complete words, "D" stands for Design, "E" stands for Engineering and "M" stands for Manufacturing.
Even if you feel all these three terms are similar, that is not. Each one has its objectives.
In geometries, this word is used for shapes that lose their characteristics or that are not generated correctly. Degeneracies can arise due to issues in geometry (parametric) or topology. When parametric space is incompatible with the real world of the geometric model, degeneracy is created. Degeneration can happen not only for edges but also for curves, and faces. Degeneracy is not this kind is not harmful in and of itself. These shapes can be used in Boolean operations, and mesh. Degeneracies that happen after a Boolean operation will cause problems and at that time, we need to be aware of its existence.
Degenerate boundary is an incomplete or zero-area loop, or an incomplete or zero-volume shell.
An operator is a symbol designed to operate on data.
They can be a single symbol, di-graphs, tri-graphs or keywords.
Operators can be classified in different ways.
This is similar to function overloading
The basic meaning of the buffer is a memory block of a computer that acts as a temporary placeholder. Buffer is used in different fields and the most common examples are video streaming and RAM. In programming, a software buffer is denoted by a place that keeps data before the process is started. That will be fast rather than data writing in a direct way. People tend to use “buffer” when data is moving around. The reason is that the data will be temporarily placed in a buffer and move to the final destination afterward. When the receiving data rate is different from the processing data rate, buffers are very useful. You will get to know this while video streaming.
Open CASCADE Technology (OCCT) is a C++ library that is designed for the production of domain-specific CAD/CAM applications. The most important feature of this library is it is free. But the applicability and capacity of this library are huge. Many open-source CAD/CAM products are based on this. With the help of a huge community and development team, developers, users, researchers, and commercial product developers can use it for different industrial applications, research, and many more.
The mechanism is an assembly of machine components (Kinematic Links) designed to obtain the desired motion from an available motion while transmitting appropriate forces and moments.
Four bar linkage is a simple planer mechanism which has four bar shaped members. Usually it has one fixed link and three moving links and four pin joints.
This presentation was prepared to present on behalf of judges of IESL to achieve IESL Industrial Training Award 2020.
Here I included a summary of activities and project experience which performed during the training period.
“Araliya Mushrooms” is a business firm situated in Baddegama, Galle which was founded in 2013. The business started on a small scale with only 2 people and now the firm is expanded within 5 years of time. There are 5 people currently working in the firm. “Araliya mushrooms” firm is the largest mushroom production firm in that region. The main target customers of the business are small scale vegetable vendors.
Computational and experimental investigation of aerodynamics of flapping aero...Lahiru Dilshan
Renewal interest on the exploitation of flapping flight motions to attain high propulsion efficiency of air vehicles is inspired by the aerodynamics of birds’ and insects’ flights. The flapping characteristics can be majorly used to develop micro aerial vehicles (MAV) as this is a lucrative method to generate lift and thrust simultaneously. In this project, the variation of the flow properties and the thrust generation of an airfoil in a flapping (plunging) motion, is evaluated using both computational and experimental methods. The NACA 2412 airfoil was selected for the study and, the computational method was carried out using an inviscid flow model and computational fluid dynamics (CFD) simulations, simultaneously to obtain and compare the variation of properties.
The inviscid model was developed using conformal mapping and potential flow theories, and it is capable of producing results for any arbitrary aerofoil. Steady-state results were compared and validated in both CFD and inviscid flow modelling as the computational framework along with flow visualisation and force sensing as the experimental framework. The validated CFD and inviscid models have been developed to produce a plunging motion to the aerofoil and obtain the variation of drag and lift coefficients with time. The experimental setup was designed to obtain the forces acting on the airfoil, and the flow characteristics were visually observed using a flow visualization technique. The force calculations were done through a developed and optimized load cell arrangement. The developed smoke flow visualisation technique is capable of successfully capturing streamline patterns, flow separation regions. These results were compared along with wake development between computational and experimental models. The Level of agreement and limitations of each method have been discussed in this report.
Experimental and numerical stress analysis of a rectangular wing structureLahiru Dilshan
Structures of an aircraft can be categorised as primary structural components and secondary structure components. Primary structure components are the components which lead to failure of the aircraft if such component is failed during the flight cycle. Secondary components are load sharing components in an aircraft but will not pave the way to catastrophic failure.
Designing aircraft structures should follow several strategies to assure safety. For that, there are three main methods used in designing and maintenance procedures. First one is the safe flight, which an aircraft component has a lifetime. That component is not used beyond that limit and should replace though it is not failed. The fail-safe method is another one that redundant systems or components are there to ensure there is another way to carry the load or do necessary control. The final one is the damage tolerance which measures the current damages are within acceptable limit and carry out the main functions until the next main maintenance process.
To determine the safety of a structure component load distribution, stress and strain variation, deflection can be used as parameters to make sure that component can withstand maximum allowable load with safety factor. There are several techniques used to get accurate results as numerical methods, Finite Element Method (FEM) and experimental methods. In the design process, those three steps are followed in an orderly manner to ensure the safety of an aircraft.
Experimental and numerical stress analysis of a rectangular wing structureLahiru Dilshan
Structures of an aircraft can be categorised as primary structural components and secondary structure components. Primary structure components are the components which lead to failure of the aircraft if such component is failed during the flight cycle. Secondary components are load sharing components in an aircraft but will not pave the way to catastrophic failure.
Designing aircraft structures should follow several strategies to assure safety. For that, there are three main methods used in designing and maintenance procedures. First one is the safe flight, which an aircraft component has a lifetime. That component is not used beyond that limit and should replace though it is not failed. The fail-safe method is another one that redundant systems or components are there to ensure there is another way to carry the load or do necessary control. The final one is the damage tolerance which measures the current damages are within acceptable limit and carry out the main functions until the next main maintenance process.
To determine the safety of a structure component load distribution, stress and strain variation, deflection can be used as parameters to make sure that component can withstand maximum allowable load with safety factor. There are several techniques used to get accurate results as numerical methods, Finite Element Method (FEM) and experimental methods. In the design process, those three steps are followed in an orderly manner to ensure the safety of an aircraft.
Transient three dimensional cfd modelling of ceilng fanLahiru Dilshan
Ceiling fans are used to get thermal comfort, especially in tropical countries. With the increment of the usage of air conditioners, the emission of CO2 is increased. But ceiling fans are a limited solution, that saves much energy compared to air conditioners. Ceiling fans generate a non-uniform velocity profile, so that, there is a non-uniform thermal environment. That non-uniform environment does not imply lower thermal comfort, that will give enough thermal comfort with low energy cost by air velocity. Hence, there will be difficulties of analysing with simple modelling techniques in that environment. So, to predict the performance of the ceiling fan required more accurate models.
The accurate model of a ceiling fan will generate complex geometry that makes difficulties for the simulation process and requires higher computational power. Because of that, there are several methods used to predict the performance of the ceiling fan using mathematical techniques but that will give an estimated value of properties in the surrounding.
General inclusion: flight crew, passengers, munitions, cargo, scientific instruments or experiments, and other equipment aboard.
General Discipline:
Prevention of accidents and incidents
Protection of aircraft occupants
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study of how humans behave physically and psychologically in relation to particular environments, products, or services. application of psychological and physiological principles to the engineering and design of products, processes, and systems.
Human factors - Maintenance and inspectionLahiru Dilshan
Maintenance information should be understandable by the technicians and inspectors. Therefore new manuals, job cards and service bulletins should be tested before distribution.
Passengers are more and more demanding in terms of comfort. Therefore thermal comfort inside the cabin is more important.The state of mind, which expresses satisfaction with the thermal environment- ISO 7730
Displays and controls arrangement of military aircraftLahiru Dilshan
In modern-day military aviation, displays are the most
a reliable method of presenting information to the pilots,
with the increment of more sophisticated controls
given to the pilots.
Final project report on grocery store management system..pdfKamal Acharya
In today’s fast-changing business environment, it’s extremely important to be able to respond to client needs in the most effective and timely manner. If your customers wish to see your business online and have instant access to your products or services.
Online Grocery Store is an e-commerce website, which retails various grocery products. This project allows viewing various products available enables registered users to purchase desired products instantly using Paytm, UPI payment processor (Instant Pay) and also can place order by using Cash on Delivery (Pay Later) option. This project provides an easy access to Administrators and Managers to view orders placed using Pay Later and Instant Pay options.
In order to develop an e-commerce website, a number of Technologies must be studied and understood. These include multi-tiered architecture, server and client-side scripting techniques, implementation technologies, programming language (such as PHP, HTML, CSS, JavaScript) and MySQL relational databases. This is a project with the objective to develop a basic website where a consumer is provided with a shopping cart website and also to know about the technologies used to develop such a website.
This document will discuss each of the underlying technologies to create and implement an e- commerce website.
Hybrid optimization of pumped hydro system and solar- Engr. Abdul-Azeez.pdffxintegritypublishin
Advancements in technology unveil a myriad of electrical and electronic breakthroughs geared towards efficiently harnessing limited resources to meet human energy demands. The optimization of hybrid solar PV panels and pumped hydro energy supply systems plays a pivotal role in utilizing natural resources effectively. This initiative not only benefits humanity but also fosters environmental sustainability. The study investigated the design optimization of these hybrid systems, focusing on understanding solar radiation patterns, identifying geographical influences on solar radiation, formulating a mathematical model for system optimization, and determining the optimal configuration of PV panels and pumped hydro storage. Through a comparative analysis approach and eight weeks of data collection, the study addressed key research questions related to solar radiation patterns and optimal system design. The findings highlighted regions with heightened solar radiation levels, showcasing substantial potential for power generation and emphasizing the system's efficiency. Optimizing system design significantly boosted power generation, promoted renewable energy utilization, and enhanced energy storage capacity. The study underscored the benefits of optimizing hybrid solar PV panels and pumped hydro energy supply systems for sustainable energy usage. Optimizing the design of solar PV panels and pumped hydro energy supply systems as examined across diverse climatic conditions in a developing country, not only enhances power generation but also improves the integration of renewable energy sources and boosts energy storage capacities, particularly beneficial for less economically prosperous regions. Additionally, the study provides valuable insights for advancing energy research in economically viable areas. Recommendations included conducting site-specific assessments, utilizing advanced modeling tools, implementing regular maintenance protocols, and enhancing communication among system components.
CFD Simulation of By-pass Flow in a HRSG module by R&R Consult.pptxR&R Consult
CFD analysis is incredibly effective at solving mysteries and improving the performance of complex systems!
Here's a great example: At a large natural gas-fired power plant, where they use waste heat to generate steam and energy, they were puzzled that their boiler wasn't producing as much steam as expected.
R&R and Tetra Engineering Group Inc. were asked to solve the issue with reduced steam production.
An inspection had shown that a significant amount of hot flue gas was bypassing the boiler tubes, where the heat was supposed to be transferred.
R&R Consult conducted a CFD analysis, which revealed that 6.3% of the flue gas was bypassing the boiler tubes without transferring heat. The analysis also showed that the flue gas was instead being directed along the sides of the boiler and between the modules that were supposed to capture the heat. This was the cause of the reduced performance.
Based on our results, Tetra Engineering installed covering plates to reduce the bypass flow. This improved the boiler's performance and increased electricity production.
It is always satisfying when we can help solve complex challenges like this. Do your systems also need a check-up or optimization? Give us a call!
Work done in cooperation with James Malloy and David Moelling from Tetra Engineering.
More examples of our work https://www.r-r-consult.dk/en/cases-en/
Sachpazis:Terzaghi Bearing Capacity Estimation in simple terms with Calculati...Dr.Costas Sachpazis
Terzaghi's soil bearing capacity theory, developed by Karl Terzaghi, is a fundamental principle in geotechnical engineering used to determine the bearing capacity of shallow foundations. This theory provides a method to calculate the ultimate bearing capacity of soil, which is the maximum load per unit area that the soil can support without undergoing shear failure. The Calculation HTML Code included.
Hierarchical Digital Twin of a Naval Power SystemKerry Sado
A hierarchical digital twin of a Naval DC power system has been developed and experimentally verified. Similar to other state-of-the-art digital twins, this technology creates a digital replica of the physical system executed in real-time or faster, which can modify hardware controls. However, its advantage stems from distributing computational efforts by utilizing a hierarchical structure composed of lower-level digital twin blocks and a higher-level system digital twin. Each digital twin block is associated with a physical subsystem of the hardware and communicates with a singular system digital twin, which creates a system-level response. By extracting information from each level of the hierarchy, power system controls of the hardware were reconfigured autonomously. This hierarchical digital twin development offers several advantages over other digital twins, particularly in the field of naval power systems. The hierarchical structure allows for greater computational efficiency and scalability while the ability to autonomously reconfigure hardware controls offers increased flexibility and responsiveness. The hierarchical decomposition and models utilized were well aligned with the physical twin, as indicated by the maximum deviations between the developed digital twin hierarchy and the hardware.
Cosmetic shop management system project report.pdfKamal Acharya
Buying new cosmetic products is difficult. It can even be scary for those who have sensitive skin and are prone to skin trouble. The information needed to alleviate this problem is on the back of each product, but it's thought to interpret those ingredient lists unless you have a background in chemistry.
Instead of buying and hoping for the best, we can use data science to help us predict which products may be good fits for us. It includes various function programs to do the above mentioned tasks.
Data file handling has been effectively used in the program.
The automated cosmetic shop management system should deal with the automation of general workflow and administration process of the shop. The main processes of the system focus on customer's request where the system is able to search the most appropriate products and deliver it to the customers. It should help the employees to quickly identify the list of cosmetic product that have reached the minimum quantity and also keep a track of expired date for each cosmetic product. It should help the employees to find the rack number in which the product is placed.It is also Faster and more efficient way.
block diagram and signal flow graph representation
Volumetric efficient of a compressor
1. VOLUMETRIC EFFICIENCY OF A
COMPRESSOR
EXPERIMENT NO.:
INSTRUCTED BY:
GROUP MEMBERS:
NAME :
COURSE : BSc. Engineering
INDEX NO. : 150
GROUP :
DATE OF PER. :
DATE OF SUB. :
2. INTRODUCTION:
In most of the manufacturing processes use compressed air or liquid. They are used in various
processes. As an example, to work with pneumatic tools, need high pressure air, can provide using
compressor. The use of compressor can be categorized under three headings, power service, process
service and control.
In power service, air or liquid is used to produce motion or to develop force or both in same time. In
actuators that using air, pneumatic tools are some of the examples. The meaning of the power service
is an application in which air or other gas enters into a process itself. As an instance combustion use
air to produce power itself. Control applications that use are control triggers, start stop modulates or
direct machine processes.
Mainly compressors are used to increase the pressure of the air in mechanically means. Most of the
industries are used compressed air but some of the special purpose industries are used Nitrogen,
Oxygen as the requirement of them.
There are various types of compressors. Mainly they divide in to two categories, positive displacement
and dynamic. Again, positive displacement compressors are divided in to two categories, rotary and
reciprocating. And also, dynamic compressors are divided in to two categories as centrifugal and axial.
Positive displacement compressors are usually reciprocating piston type. They can be used to supply
small amount of air with high pressure. In centrifugal compressors increase kinetic energy of the gas
using impeller, and convert energy into increase pressure in a divergent outlet passage. To compress
moderately large amount of gas to moderate pressures, use centrifugal compressors. In axial
compressors gas flow through series of blades and when it passes through various blades velocity
fluctuation happens and when increase the kinetic energy that convert in to pressure energy. These
types of compressors used in mainly jet engines, gas turbines.
3. THEORY:
By definition;
Volumetic Efficeincy (ƞ) =
Volume of free air deleivered per min (Vinduced)
Volume swept by the piston per min( Vswept)
Free air delivery = K ×
t1 + 273
P1
+ √
H × M2
t + 273
K = 7.52 × 10−2
(Nozzle coefficient)
t = Nozzle temperature
H = Observed head in mm of H2O (upstream)
M2 = P1 −
h
13.6
in mm of Hg
P1 = Barometer reading in mm of Hg
h = Observed head in mm of H2O (downstream)
t1 = Atmospheric air temperature
Vswept =
π d2
4
× l × V × N
(Seattlr pi, 2017)
D = Diameter of the bore
l = Stroke length
V = motor speed (450 rpm)
N = number of cylinders.
4. PROCEDURE
• The valves of cooling water supply and discharge lines are fully opened.
• Then the motor is fully unloaded and started.
• The air compressor is started and the unit is allowed to function at 300rpm for about ten
minutes.
• Then the test is commenced and required readings are taken.
• The pressure at air receiver is kept constant at the required value while taking the reading and
the constant speed of 300 rpm is maintained.
• Note down the height of the liquid columns to calculate the pressure
• Change the speed of the motor and repeat the practical for another value.
5. CALCULATIONS:
Data:
No: of cylinders : 2
Bore : 101.6 mm
Stroke : 101.6 mm
Calculations are done and shown for the test 2
𝑃𝑑𝑒𝑙𝑖𝑣𝑒𝑟𝑦 = 10 𝑝𝑠𝑖
𝑇𝑑𝑒𝑙𝑖𝑣𝑒𝑟𝑦 = 30.5 ℃
H = 92 mm
h = 24 mm
𝑀2 = 762.5 −
24
13.6
= 760.735 𝑚𝑚𝐻𝑔
Free air delivery = 7.52 × 10−2
×
30 + 273
762.5
× √
92 × 760.735
30 + 273
= 0.4542 m3/min
Vswept =
π × (101.6 × 10−3
)2
4
× 101.6 × 10−3
× 300 × 2
= 0.4942 m3/min
Volumetic Efficeincy (ƞ) =
0.4542 m3/min
0.4942 m3/min
× 100 %
= 91.9 %
6. RESULTS:
For compressor 300 rpm
For Compressor 400 rpm
Test P (delivery)
(Psi)
T (delivery)
(℃)
H
(mm)
h
(mm)
Free air
delivery
(m3/min)
Swept
Volume
(m3/min)
Efficiency
(%)
1 10 30 92 24 0.4542 0.4942 91.9
2 20 30.5 57 19 0.3582 0.4942 72.47
3 30 30.5 83 20 0.4322 0.4942 87.45
4 40 30.5 56 14 0.3551 0.4942 71.85
5 50 31 53 16 0.3460 0.4942 70.01
Test P (delivery)
(Psi) T (delivery)
(℃)
H
(mm)
h
(mm)
Free air
delivery
(m3/min)
Swept
Volume
(m3/min)
Efficiency
(%)
1 10 30.5 179 50 0.6337 0.659 96.17
2 20 31 71 21 0.4003 0.659 60.75
3 30 31 122 21 0.5248 0.659 79.64
4 40 21 99 16 0.4729 0.659 71.75
5 50 31 115 32 0.5092 0.659 77.28
7. For compressor 500 rpm
Test P (delivery)
(Psi)
T (delivery)
(℃)
H
(mm)
h
(mm)
Free air
delivery
(m3/min)
Swept
Volume
(m3/min)
Efficiency
(%)
1 10 30.5 221 54 0.7040 0.8237 85.47
2 20 30.5 92 21 0.4550 0.8237 55.24
3 30 31 57 33 0.3585 0.8237 43.52
4 40 31.5 176 42 0.6307 0.8237 76.57
5 50 32 242 59 0.7402 0.8237 89.86
9. Free air delivery vs rpm
For 10 psi
rpm Free air delivery
300 0.45
400 0.63
500 0.70
For 20 psi
rpm Free air delivery
300 0.36
400 0.40
500 0.46
For 30 psi
rpm Free air delivery
300 0.43
400 0.52
500 0.36
For 40 psi
rpm Free air delivery
300 0.36
400 0.47
500 0.63
For 50 psi
rpm Free air delivery
300 0.35
400 0.51
500 0.74
10. DISCUSSION
• Usefulness of the lab exercise and engineering application
Piston engines are used in many applications in engineering world. So that we have to get maximum
efficiency from these engines and reduce wastage of the energy. In order to get some knowledge,
we are going to get the understanding of the volumetric efficiency varies according to load.
Through that results we can get an idea in which load we have to use and the running speed of the
machine that deliver maximum efficiency. Mainly these results are used in automobile industry.
And also, refrigeration and ac, pneumatic tool industries use these results. In other words, we can
say that these results are going to help all the industries that use piston engines, gas turbines and
industries that use high pressure liquids and gases.
Mainly in designing piston engines they are going to consider how much air is going to compress
and the pressure increase inside the cylinders. With the practical testing, they come to know that
what are the best compression ratios that the material of the piston engine can withstand. In the
boiler making industry also same. Most of the industrial applications are based on metallurgical
limits of the components and if they can use maximum limits of the properties of the gases or
liquids, it comes to cost effective. So that these practical results are going to design components as
well as increase cost effectiveness of the industry.
• Volumetric efficiency of an air compressor
Volumetric efficiency is the ratio between the volume of free air delivered to the compressor per
unit time and volume swept by the piston per unit time. More specifically, volumetric efficiency is
a ratio (or percentage) of the quantity of air that is trapped by the cylinder during induction over the
swept volume of the cylinder under static conditions. In the case of forced induction volumetric
efficiency can exceed 100%.
Basically, volumetric efficiency is reduced than that appears because of the clearance volume, that
have to take for account. That causes the difference between theoretical and practical values that
comes from the volume of air compressed inside the cylinder. When gas is compressed and delivered
through the discharge valves, all the gas doesn’t discharge and remain some amount, that causes the
clearance volume. When piston goes down, suction valve is not open immediately with the
movement of the piston because of the high pressure inside. That makes clearance volume. So that
gas used in suction stroke goes unused and reduces the volumetric efficiency of the compressor.
• Factors that affect volumetric efficiency
1. Induction and exhaust system flow friction – because of the flow friction, pressure drops occur
in the inlet across the air filter.
2. Induction system heat transfer
3. Valve time effects –
a. At low engine speed, amount of mixture that entered the cylinder during the intake is
pushed back into the intake by moving piston, during the compression stroke prior to
inlet valve closing
b. At high engine speed, high momentum of the air in the intake manifold towards the
cylinder set up during the intake stroke forces additional air into the cylinder while the
intake valve remains open
c. During the valve overlap period between inlet valve opening and exhaust valve closing,
both valves are open. The amount of overlap, and engine speed, affect the residua
friction
11. 4. Valve flow friction
5. In cylinder heat transfer – incoming air is cooler than the cylinder walls. So that heat transfer
from walls to air decrease the density of the air.
6. Intake tuning
7. Delivery pressure
8. Clearance volume of the piston
9. Number of stages in the compressor
10. Speed of rotation of the compressor
11. Operating temperature
12. Valve operating speed
13. Method of cooling
14. Method of closing isothermal processes.
• Meaning of free air delivery
That means actual quantity of compressed air converted back to the inlet conditions of the
compressor. Actually, this measures the internal capacity of compressor. That is the actual air
compressed at the inlet condition of the compressor. In good compressor, free air delivery should
be higher to make the cooling process much more effective.
• According to the steady flow energy equation, the possible variation of pressure and
temperature along the line from the compressor outlet to the orifice meter.
Temperature Variation
There are many ways of temperature varying along the compressor outlet to the orifice meter. Such
as,
a) Temperature drop at the outlet pipe.
The outlet pipe line is long to a certain extent and because of that heat transfer is happened
between the pipe line and the atmosphere.
b) Temperature drop at the pressure controlling gate
The turbulence created by the opening and the closing mechanism will help to destroy some
kinetic energy of the flow, hence resulted in drop of temperature.
c) Temperature drops at the storing tank.
Some amount of heat energy will be wasted to the environment in the storage tank, which
resulted in reduction in temperature.
Pressure Variation
In the practical pressurized air is stored in the tank and then released in to the orifice meter. So that
there should be pressure drop at the outlet of the tank and also inlet of the tank from the
compressor. And also, - there are several gates and valves that air must go through, causes some
pressure drop.
• Accurate method of measuring the absolute pressure upstream of the orifice meter.
We use u tube to get the pressure at the orifice. To get accurate results we have to increase the height
of the liquid columns. That reduce the reading errors. Here we have to use liquid that has density lower
than the liquid that we are using in the practical.
12. And also, if we can use calibrated pressure sensors rather than U tube, we can directly measure
pressure accurately and reduce human errors that will affect.
• Discrepancies observed between the experimental values and the expected values
Mainly these changes accrue because of the human errors and equipment errors. Rather than that,
the liquids and gases are not ideal one because they are real and have deviations from the ideal gas
behavior. We develop our system using ideal behavior of the substances. So that makes an error.
And also, there are heat losses in the system. Compressor test rig is consisting of longer steel tube,
that dissipate heat to the outside.
The speed of the engine is not constant during the practical so that the final values will deviate
from the others. And also, temperature of the atmosphere will change. That also affect the
practical.
We use some rounded numbers because we have to convert some values into another measuring
systems. That will make small errors.
• Suggestions to minimize errors.
Tubes and other steel parts must be covered to avoid heat rejection to the outside.
Have to use keen eye to read the heights of the liquid columns
Temperature and heights of the liquid columns must be read in eye level
Readings must be taken as fast as possible because the state will change rapidly.
References
Global, M. (2017). Expert air compressors. Retrieved from Air compressors:
https://www.expertmarket.co.uk/air-compressors/What-is-the-Volumetric-Efficiency-of-Air-
Compressors?question_page=4
K., A. (2011, march 27). Bright Hub Engineering. Retrieved from Mechanical Engineering:
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