title: Vacuum Steam Desuperheating and Condensation: An Experimental Investigation

authors: Lokhande, Akash

abstract: Steam condensation plays an essential role in supplying and removing heat in many industrial applications, including the energy sector. It therefore is a phenomena of significance that requires deep understanding. This thesis presents effective vacuum steam condensation on the shell-side of vertical shell and tube condenser (VSTC) accompanying steam desuperheating. It describes a fundamental study of heat transfer in VSTC with considerations of several factors; explicitly degree of superheat related with each vacuum steam pressure, temperature waviness in desuperheating section, and steam condensation in absence of non-condensable gas (NCG). Experiments performed on the VSTC are: 
Steam desuperheating and condensation in the shell-side VSTC at a variety of vacuum steam pressures and respective steam flowrates, vacuum steam desuperheating and condensation in the shell-side of VSTC at reduced steam flowrates, and vacuum steam desuperheating and condensation at tube wall temperatures up to steam saturation temperature (T₂ ≥ Tsat) to analyse dry heat transfer in the desuperheating section. To examine the stated aim, test facility was built in the laboratory of the University of Waikato.
By generating desuperheating and condensation models for each test pressure, this investigation proves that vacuum steam condensation best occurs without involvement of superheat. About 60% of the VSTC occupied with desuperheating, and the heat transfer involved in desuperheating is minor approximately 1 kW, whereas, the condensation section of VSTC has heat transfer about 10 kW. By reducing the steam flowrate, 10% reduction in the desuperheating section and 20% to 50% reduction in the Reynolds number was observed. After raising the tube wall temperature up to the steam saturation temperature, a smooth temperature profile across the desuperheating the section was seen with significant sensible heat transfer. Obstruction linked with superheated steam condensation in the dairy industrial leads to poor heat transfer area utilization by the desuperheating section and therefore, reduction of the evaporator rating or oversizing of the heat exchangers to attain appropriate duty.

text: Vacuum Steam Desuperheating and Condensation: An Experimental Investigation Steam condensation plays an essential role in supplying and removing heat in many industrial applications, including the energy sector. It therefore is a phenomena of significance that requires deep understanding. This thesis presents effective vacuum steam condensation on the shell-side of vertical shell and tube condenser (VSTC) accompanying steam desuperheating. It describes a fundamental study of heat transfer in VSTC with considerations of several factors; explicitly degree of superheat related with each vacuum steam pressure, temperature waviness in desuperheating section, and steam condensation in absence of non-condensable gas (NCG). Experiments performed on the VSTC are: 
Steam desuperheating and condensation in the shell-side VSTC at a variety of vacuum steam pressures and respective steam flowrates, vacuum steam desuperheating and condensation in the shell-side of VSTC at reduced steam flowrates, and vacuum steam desuperheating and condensation at tube wall temperatures up to steam saturation temperature (T₂ ≥ Tsat) to analyse dry heat transfer in the desuperheating section. To examine the stated aim, test facility was built in the laboratory of the University of Waikato.
By generating desuperheating and condensation models for each test pressure, this investigation proves that vacuum steam condensation best occurs without involvement of superheat. About 60% of the VSTC occupied with desuperheating, and the heat transfer involved in desuperheating is minor approximately 1 kW, whereas, the condensation section of VSTC has heat transfer about 10 kW. By reducing the steam flowrate, 10% reduction in the desuperheating section and 20% to 50% reduction in the Reynolds number was observed. After raising the tube wall temperature up to the steam saturation temperature, a smooth temperature profile across the desuperheating the section was seen with significant sensible heat transfer. Obstruction linked with superheated steam condensation in the dairy industrial leads to poor heat transfer area utilization by the desuperheating section and therefore, reduction of the evaporator rating or oversizing of the heat exchangers to attain appropriate duty.

year: 2015

title: Characterisation, Consolidation and Mechanical Properties of TiAl Alloy Produced Using Titanox Powders

authors: Parmar, Bhupinder

subjects: TiAl alloys

abstract: Characterization of the three different as- received TiAl powders, namely Tax1, Tax2 and Tax3 produced by Titanox development Ltd has been done. Predominate TiAl phase was observed in all the three compositions .The powder particles were very fine with average particle size of 12μm, 5μm and 10μm respectively for Tax1, Tax2 and Tax3.Chemical analysis of the powders showed high oxygen content in all the three compositions of the powders .
Bulk samples were produced from Tax1, Tax2 and Tax3 powders by hot isostatic pressing at 1200  C under a pressure of 200Mpa for two hours .The pressurization gas used for the process was argon. The relative density of Tax1, Tax2 and Tax3 HIPped samples was 96%, 86% and 93%and respectively. The characterization of the HIPped samples showed that the predominate phase was γ-TiAl phase in all the three HIPped samples .A small fractions of Ti3Al and TiAl3 was also observed in tax1 and Tax3 HIPped material. Also some of the dark Al rich phases was Al2O3 phase in Tax1 and Tax3 HIPped samples. High oxygen content of the powder and air leaking in the can during the process of press-seal and welding of the end of the tube of the can prior to HIPping lead to poor consolidation of Tax2 which eventually resulted in high porosity and formation of Ti2O and Al2O3. Half of the Tax2 HIPped sample was canned and heated to 1160 C and was subjected to open die hammer forging with a high strain and a total reduction of height by 66% .The forging produced a pancake shaped sample without breaking of the sample.
Tensile specimens were cut from the Tax1 and Tax3 HIPped sample and one from the Tax2 forged sample using electrical discharge machine (EDM) wirecutting. Tax1 HIPped material showed the average fracture strength of 204MPa, 256MPa and 197MPa at room temperature, 800 C and 900 C respectively., Whereas Tax3 HIPped material showed average fracture strength of 103MPa and 234MPa respectively at room temperature and 800 C respectively. The HIPped and the forged Tax2 sample showed low fracture strength of 91MPa because of the micro-cracks produced during forging.

text: Characterisation, Consolidation and Mechanical Properties of TiAl Alloy Produced Using Titanox Powders Characterization of the three different as- received TiAl powders, namely Tax1, Tax2 and Tax3 produced by Titanox development Ltd has been done. Predominate TiAl phase was observed in all the three compositions .The powder particles were very fine with average particle size of 12μm, 5μm and 10μm respectively for Tax1, Tax2 and Tax3.Chemical analysis of the powders showed high oxygen content in all the three compositions of the powders .
Bulk samples were produced from Tax1, Tax2 and Tax3 powders by hot isostatic pressing at 1200  C under a pressure of 200Mpa for two hours .The pressurization gas used for the process was argon. The relative density of Tax1, Tax2 and Tax3 HIPped samples was 96%, 86% and 93%and respectively. The characterization of the HIPped samples showed that the predominate phase was γ-TiAl phase in all the three HIPped samples .A small fractions of Ti3Al and TiAl3 was also observed in tax1 and Tax3 HIPped material. Also some of the dark Al rich phases was Al2O3 phase in Tax1 and Tax3 HIPped samples. High oxygen content of the powder and air leaking in the can during the process of press-seal and welding of the end of the tube of the can prior to HIPping lead to poor consolidation of Tax2 which eventually resulted in high porosity and formation of Ti2O and Al2O3. Half of the Tax2 HIPped sample was canned and heated to 1160 C and was subjected to open die hammer forging with a high strain and a total reduction of height by 66% .The forging produced a pancake shaped sample without breaking of the sample.
Tensile specimens were cut from the Tax1 and Tax3 HIPped sample and one from the Tax2 forged sample using electrical discharge machine (EDM) wirecutting. Tax1 HIPped material showed the average fracture strength of 204MPa, 256MPa and 197MPa at room temperature, 800 C and 900 C respectively., Whereas Tax3 HIPped material showed average fracture strength of 103MPa and 234MPa respectively at room temperature and 800 C respectively. The HIPped and the forged Tax2 sample showed low fracture strength of 91MPa because of the micro-cracks produced during forging.

year: 2007

title: Māori women’s perspectives of leadership and wellbeing

authors: Ruru, Stacey Mariu

subjects: Māori leadership

abstract: Within Aotearoa, New Zealand, Māori women are engaged in leadership roles in community and professional workplace settings, however little is known about how they maintain their wellbeing. This research sought to unravel how Māori women leaders maintain their wellbeing, while occupied in complex leadership roles. We report on the findings from semi-structured interviews, acknowledging kaupapa Māori theory and principles, with five Māori women leaders. Thematic analysis was used, and these themes related to five whakataukī (proverb) that provided overarching themes and directions relating to Māori women’s leadership and wellbeing. Each whakataukī describe unique aspects of leadership and wellbeing from a Māori worldview. Themes include humility, collectiveness, courage, future orientations and positivity. While the themes are housed in whakataukī, central to the success of these Māori women leaders was being connected to whānau (family) and friends, and being influenced by tamariki (children), tauira (students) and employees. These social connections made Māori women leaders strong and resilient to change and challenges.

text: Māori women’s perspectives of leadership and wellbeing Within Aotearoa, New Zealand, Māori women are engaged in leadership roles in community and professional workplace settings, however little is known about how they maintain their wellbeing. This research sought to unravel how Māori women leaders maintain their wellbeing, while occupied in complex leadership roles. We report on the findings from semi-structured interviews, acknowledging kaupapa Māori theory and principles, with five Māori women leaders. Thematic analysis was used, and these themes related to five whakataukī (proverb) that provided overarching themes and directions relating to Māori women’s leadership and wellbeing. Each whakataukī describe unique aspects of leadership and wellbeing from a Māori worldview. Themes include humility, collectiveness, courage, future orientations and positivity. While the themes are housed in whakataukī, central to the success of these Māori women leaders was being connected to whānau (family) and friends, and being influenced by tamariki (children), tauira (students) and employees. These social connections made Māori women leaders strong and resilient to change and challenges.

year: 2017