Preconditioning measurement and control system for a combustion engine in a vehicle
- Authors: Homann, Gregor
- Date: 2011
- Subjects: Internal combustion engines , Mechanical engineering
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9649 , http://hdl.handle.net/10948/d1010998 , Internal combustion engines , Mechanical engineering
- Description: Modern vehicles have to ful ll new CO2 emission and additionally customer comfort requirements to stay competitive. A major impact to the fuel consumption of an internal combustion engine (ICE) has the starting period. An ICE equipped with a preconditioning system which heats up the ICE much faster than a common ICE. This procedure of preconditioning is called peak heating. The main benet of preconditioning of an ICE is less fuel consumption. Recently the only way to obtain a fast heating up of an ICE is the injection of a higher amount of fuel during the starting period. This heat up procedure can be changed if a heat reservoir is available to the ICE during the starting period. In this case the additional injection of fuel is redundant and therefore the consumption during the starting period can be reduced. The major advantages of this strategy are achieved in cold ambient conditions. During this project di erent preconditioning strategies and di erent points of interaction in the coolant circuit of an ICE have been investigated. The preconditioning concepts have been evaluated according to their heating up performance and their implementation into the engine compartment. The results obtained by this project highlight that a system layout which enables a preheating of the cylinder block by a heat reservoir located in a bypass-line to the heater core is the most e ective point of interaction. The best results have been achieved with a coolant ow of 10 l/min at a temperature of 90 C. Furthermore, this project points out that the implementation of a preconditioning system into the oil cooler will achieve similar results. This strategy of preconditioning the engine oil reduces the internal frictions of the ICE which leads to a decreasing consumption. This solution is much more energy e cient and technically easier to implement into a modern vehicle with its limited space. An additional side e ect of the preconditioning of the oil is a longer service life of the ICE.
- Full Text:
- Date Issued: 2011
- Authors: Homann, Gregor
- Date: 2011
- Subjects: Internal combustion engines , Mechanical engineering
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9649 , http://hdl.handle.net/10948/d1010998 , Internal combustion engines , Mechanical engineering
- Description: Modern vehicles have to ful ll new CO2 emission and additionally customer comfort requirements to stay competitive. A major impact to the fuel consumption of an internal combustion engine (ICE) has the starting period. An ICE equipped with a preconditioning system which heats up the ICE much faster than a common ICE. This procedure of preconditioning is called peak heating. The main benet of preconditioning of an ICE is less fuel consumption. Recently the only way to obtain a fast heating up of an ICE is the injection of a higher amount of fuel during the starting period. This heat up procedure can be changed if a heat reservoir is available to the ICE during the starting period. In this case the additional injection of fuel is redundant and therefore the consumption during the starting period can be reduced. The major advantages of this strategy are achieved in cold ambient conditions. During this project di erent preconditioning strategies and di erent points of interaction in the coolant circuit of an ICE have been investigated. The preconditioning concepts have been evaluated according to their heating up performance and their implementation into the engine compartment. The results obtained by this project highlight that a system layout which enables a preheating of the cylinder block by a heat reservoir located in a bypass-line to the heater core is the most e ective point of interaction. The best results have been achieved with a coolant ow of 10 l/min at a temperature of 90 C. Furthermore, this project points out that the implementation of a preconditioning system into the oil cooler will achieve similar results. This strategy of preconditioning the engine oil reduces the internal frictions of the ICE which leads to a decreasing consumption. This solution is much more energy e cient and technically easier to implement into a modern vehicle with its limited space. An additional side e ect of the preconditioning of the oil is a longer service life of the ICE.
- Full Text:
- Date Issued: 2011
Characterising the stress-life response of mechanical formed AISI-1008 steel plate components
- Authors: Müller, Ruan
- Date: 2012
- Subjects: Materials -- Fatigue -- Testing , Metals -- Fatigue , Mechanical wear -- Measurement , Mechanical engineering
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9616 , http://hdl.handle.net/10948/d1008102 , Materials -- Fatigue -- Testing , Metals -- Fatigue , Mechanical wear -- Measurement , Mechanical engineering
- Description: The main purpose of this research project was to determine the fatigue-life behaviour of AISI 1008 sheet steel which has been mechanically formed to a radius of curvature of 120mm and then to correlate the fatigue-life behaviour to that of the parent or “as manufactured” material. During the forming process it was felt important to induce plastic strain through stretch-bending by clamping the sides of a plate sample’s (width) edges in the bending fixture before being bent by a single acting mechanical press. It was determined through actual testing that there was a decrease in fatigue-life when the mechanical formed data was compared to fatigue data of the parent material. Standard fatigue mathematical models were used to relate the actual fatigue data. Due to the material being cold formed to a radius of curvature of 120mm, residual stresses induced during the forming process played an essential role during the fatigue-life prediction calculations. The maximum relieved stress in the parent material was compressive in nature having a magnitude of 11percent of the “as manufactured” yield strength (265 MPa). For the mechanical formed material compressive residual stresses were measured on the outer surface while tensile stresses were measured on the inner surface. The difference between actual number of cycles to failure to that calculated using the standard mathematical models for the parent material, ranged between 48 percent and 18 percent and for the mechanical formed samples between 35 percent and 1percent, depending on the strain amplitude used. An important aspect of this study was to determine the criteria required for mathematical modelling of the parent material as testing occurred between the limit of proportionality and yield point. Although this aspect requires further investigation the mathematical results obtained during this study were considered to be acceptable.
- Full Text:
- Date Issued: 2012
- Authors: Müller, Ruan
- Date: 2012
- Subjects: Materials -- Fatigue -- Testing , Metals -- Fatigue , Mechanical wear -- Measurement , Mechanical engineering
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9616 , http://hdl.handle.net/10948/d1008102 , Materials -- Fatigue -- Testing , Metals -- Fatigue , Mechanical wear -- Measurement , Mechanical engineering
- Description: The main purpose of this research project was to determine the fatigue-life behaviour of AISI 1008 sheet steel which has been mechanically formed to a radius of curvature of 120mm and then to correlate the fatigue-life behaviour to that of the parent or “as manufactured” material. During the forming process it was felt important to induce plastic strain through stretch-bending by clamping the sides of a plate sample’s (width) edges in the bending fixture before being bent by a single acting mechanical press. It was determined through actual testing that there was a decrease in fatigue-life when the mechanical formed data was compared to fatigue data of the parent material. Standard fatigue mathematical models were used to relate the actual fatigue data. Due to the material being cold formed to a radius of curvature of 120mm, residual stresses induced during the forming process played an essential role during the fatigue-life prediction calculations. The maximum relieved stress in the parent material was compressive in nature having a magnitude of 11percent of the “as manufactured” yield strength (265 MPa). For the mechanical formed material compressive residual stresses were measured on the outer surface while tensile stresses were measured on the inner surface. The difference between actual number of cycles to failure to that calculated using the standard mathematical models for the parent material, ranged between 48 percent and 18 percent and for the mechanical formed samples between 35 percent and 1percent, depending on the strain amplitude used. An important aspect of this study was to determine the criteria required for mathematical modelling of the parent material as testing occurred between the limit of proportionality and yield point. Although this aspect requires further investigation the mathematical results obtained during this study were considered to be acceptable.
- Full Text:
- Date Issued: 2012
Influence of process energy on stress corrosion susceptibility of a friction hydro pillar repaired steam turbine rotor disc blade locating hole
- Authors: Pentz, Willem Gerhard
- Date: 2020
- Subjects: Friction welding , Mechanical engineering
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/47106 , vital:39810
- Description: Currently the power generation industry is struggling to keep older coal power plants running efficiently. One of the major hurdles is to keep repair and service cost low. Over time stress corrosion cracking (SCC) occurs in the locating pinholes of tier type rotors which locate the turbine blades. This is where this research aims to assist with an alternative repair technique, Friction Hydro Pillar Processing (FHPP) welding, to have longer service intervals thus saving cost and time. The same material can be used for welding and a new aligned hole can be drilled. FHPP welding is a solid state friction welding process. Four different FHPP axial forces were selected to compare their respective performance in subsequent tensile testing, impact testing and SCC testing. All the tensile samples extracted from preheated welds and post weld heat treated welds fracture in the parent material, which indicates good weld efficiency. The impact crack route from the weld nugget towards the parent material was identified in the energy and force graph. Axial force which promote impact toughness can be selected with this curve. SCC occurs when a tensile stress is applied to a susceptible material when in a conducive environment for cracking. A new SCC W-shape was designed and performed well during initial testing. With the SCC W-shape two specimens can be extracted opposite each other and tested. Both the preheated weld samples and the post weld heat treatment (PWHT) weld samples had improved SCC performance over their respective parent material samples. A high axial force, low process energy, and high process energy rate (low process energy and low weld time) produced a weld with improved SCC resistance. FHPP (with PWHT) is a promising repair technique as it improved on the SCC resistance and impact toughness as well as having 100% bond efficiency. More research is still required to identify the SCC mechanism of the FHPP weld.
- Full Text:
- Date Issued: 2020
- Authors: Pentz, Willem Gerhard
- Date: 2020
- Subjects: Friction welding , Mechanical engineering
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/47106 , vital:39810
- Description: Currently the power generation industry is struggling to keep older coal power plants running efficiently. One of the major hurdles is to keep repair and service cost low. Over time stress corrosion cracking (SCC) occurs in the locating pinholes of tier type rotors which locate the turbine blades. This is where this research aims to assist with an alternative repair technique, Friction Hydro Pillar Processing (FHPP) welding, to have longer service intervals thus saving cost and time. The same material can be used for welding and a new aligned hole can be drilled. FHPP welding is a solid state friction welding process. Four different FHPP axial forces were selected to compare their respective performance in subsequent tensile testing, impact testing and SCC testing. All the tensile samples extracted from preheated welds and post weld heat treated welds fracture in the parent material, which indicates good weld efficiency. The impact crack route from the weld nugget towards the parent material was identified in the energy and force graph. Axial force which promote impact toughness can be selected with this curve. SCC occurs when a tensile stress is applied to a susceptible material when in a conducive environment for cracking. A new SCC W-shape was designed and performed well during initial testing. With the SCC W-shape two specimens can be extracted opposite each other and tested. Both the preheated weld samples and the post weld heat treatment (PWHT) weld samples had improved SCC performance over their respective parent material samples. A high axial force, low process energy, and high process energy rate (low process energy and low weld time) produced a weld with improved SCC resistance. FHPP (with PWHT) is a promising repair technique as it improved on the SCC resistance and impact toughness as well as having 100% bond efficiency. More research is still required to identify the SCC mechanism of the FHPP weld.
- Full Text:
- Date Issued: 2020
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