title: Methods for improving heat exchanger area distribution and storage temperature selection in heat recovery loops

authors: Walmsley, Michael R.W.

abstract: Inter-plant Heat Integration across a large site can be achieved using a HRL (Heat Recovery Loop). In this paper the interrelationship between HRL storage temperatures, heat recovery and total HRL exchanger area is investigated. A methodology for designing a HRL based on a ΔTmin approach is compared to three programming optimisation approaches where heat exchangers are constrained to have the same NTU (Number of Heat Transfer Units), LMTD (Log-Mean Temperature Difference) or to find the absolute MTA (Minimum Total Area) for a given heat recovery level. Analysis is performed using time-averaged and transient mass flow rate data and temperature data. The actual temperature driving force of the HRL heat exchangers is compared to the apparent driving force as indicated by the Composite Curves. Results for the same heat recovery level show that the ΔTmin approach is effective at minimising total area to within 5% of the minimum area approach. Allocation of individual heat exchanger areas can vary widely depending on the optimisation method, the characteristics of the transient stream data and the differences in the approach and exit stream temperatures. Results suggest that using the ΔTmin method for selecting storage temperatures in combination with sizing exchangers based on the time average CP values (for while the process is running) gives a near optimal solution without requiring lots of data input or computing resources

text: Methods for improving heat exchanger area distribution and storage temperature selection in heat recovery loops Inter-plant Heat Integration across a large site can be achieved using a HRL (Heat Recovery Loop). In this paper the interrelationship between HRL storage temperatures, heat recovery and total HRL exchanger area is investigated. A methodology for designing a HRL based on a ΔTmin approach is compared to three programming optimisation approaches where heat exchangers are constrained to have the same NTU (Number of Heat Transfer Units), LMTD (Log-Mean Temperature Difference) or to find the absolute MTA (Minimum Total Area) for a given heat recovery level. Analysis is performed using time-averaged and transient mass flow rate data and temperature data. The actual temperature driving force of the HRL heat exchangers is compared to the apparent driving force as indicated by the Composite Curves. Results for the same heat recovery level show that the ΔTmin approach is effective at minimising total area to within 5% of the minimum area approach. Allocation of individual heat exchanger areas can vary widely depending on the optimisation method, the characteristics of the transient stream data and the differences in the approach and exit stream temperatures. Results suggest that using the ΔTmin method for selecting storage temperatures in combination with sizing exchangers based on the time average CP values (for while the process is running) gives a near optimal solution without requiring lots of data input or computing resources

year: 2013

title: Observations of shoreline–sandbar coupling on an embayed beach

authors: van de Lageweg, W.I.

subjects: shoreline

abstract: We analyse a seven-year dataset (1999–2005) of shoreline and sandbar variations derived from video observations at the embayed Tairua Beach, New Zealand, to explore sandbar–shoreline coupling and to determine how this coupling is related to alongshore-averaged sandbar–shoreline separation and beach rotation. Our results quantify the coupling between the sandbar and the shoreline which is directly related to the reduced separation between the sandbar and the shoreline. Using a simple predictive shoreline model, we show that this behaviour is related to the energy of the incoming waves. Our observations are obtained from a headland-enclosed beach and show aspects of the morphological state that relate to the existence of headlands that are not considered in the Wright and Short beach state classification. Both the sandbar and shoreline at Tairua Beach rotate relatively quickly (< 1 month) during the winter storm events, when the storms are accompanied by strong alongshore components, gradually returning during the summer months. The sandbar–shoreline coupling length scale is controlled by this rotation, with large wavelengths occurring when the sandbar is strongly rotated.

text: Observations of shoreline–sandbar coupling on an embayed beach We analyse a seven-year dataset (1999–2005) of shoreline and sandbar variations derived from video observations at the embayed Tairua Beach, New Zealand, to explore sandbar–shoreline coupling and to determine how this coupling is related to alongshore-averaged sandbar–shoreline separation and beach rotation. Our results quantify the coupling between the sandbar and the shoreline which is directly related to the reduced separation between the sandbar and the shoreline. Using a simple predictive shoreline model, we show that this behaviour is related to the energy of the incoming waves. Our observations are obtained from a headland-enclosed beach and show aspects of the morphological state that relate to the existence of headlands that are not considered in the Wright and Short beach state classification. Both the sandbar and shoreline at Tairua Beach rotate relatively quickly (< 1 month) during the winter storm events, when the storms are accompanied by strong alongshore components, gradually returning during the summer months. The sandbar–shoreline coupling length scale is controlled by this rotation, with large wavelengths occurring when the sandbar is strongly rotated.

year: 2013

title: Ora Kainga Rua: Experiences of Kura Kaupapa Māori Graduates

authors: Waller, Arianna Leigh Mana

subjects: indigenous auto ethnography

abstract: There is a wealth of indigenous scholarship examining the impacts of imperialist policies and ideologies on the learning identities of indigenous students. However, within the New Zealand context, there is a lack of literature which focuses solely on the experiences and aspirations of total immersion students to tertiary education settings. 
Using Kaupapa Māori and auto ethnography this thesis privileges the student voice by investigating the transitional experiences of four female kura Kaupapa Māori graduates into mainstream settings particularly their transition to the University of Waikato. 
The thesis argues that there are two main spaces of synergy between an indigenous research paradigm and auto ethnography. The first is the criticality of the “self” in the work, without a sharp separation between the researcher and the subject (dual meaning intended). The second is the shared modality and intentional use of storytelling as a method. By combining insights from in-depth interviews with the researcher’s life story, the thesis identified the coping mechanisms the participants employed and the services The University of Waikato provides that were utilised to help them transition into a new educational setting. 
The participants’ experiences demonstrate that the unique cultural educational experiences of kura Kaupapa Māori differ significantly from the educational and environmental experiences offered at University. The participants’ narratives demonstrated that the clear sense of identity gained from the kura Kaupapa Māori context gave them the inner strength to cope with these differences. In addition to their strong sense of Māori identity, the main coping mechanisms that the students drew on, was the wealth of institutional knowledge that family members and role models provided of the university context as past students and current staff members. The benefits that these students experienced can be strengthened by building stronger relationships between Māori total immersion schools, the wider Māori community and universities ensuring that Māori total immersion students are able to access the academic and institutional knowledge they need to succeed. 
Furthermore, the thesis argues that the kura Kaupapa Māori movement can deliver more for their students if they do not shut out the Pākehā world but rather teach their students to walk between and within the two worlds. In order to better understand this balancing act, the lived experiences of immersion students requires more research, particularly as more and more kura graduates transition into Aotearoa New Zealand tertiary settings.

text: Ora Kainga Rua: Experiences of Kura Kaupapa Māori Graduates There is a wealth of indigenous scholarship examining the impacts of imperialist policies and ideologies on the learning identities of indigenous students. However, within the New Zealand context, there is a lack of literature which focuses solely on the experiences and aspirations of total immersion students to tertiary education settings. 
Using Kaupapa Māori and auto ethnography this thesis privileges the student voice by investigating the transitional experiences of four female kura Kaupapa Māori graduates into mainstream settings particularly their transition to the University of Waikato. 
The thesis argues that there are two main spaces of synergy between an indigenous research paradigm and auto ethnography. The first is the criticality of the “self” in the work, without a sharp separation between the researcher and the subject (dual meaning intended). The second is the shared modality and intentional use of storytelling as a method. By combining insights from in-depth interviews with the researcher’s life story, the thesis identified the coping mechanisms the participants employed and the services The University of Waikato provides that were utilised to help them transition into a new educational setting. 
The participants’ experiences demonstrate that the unique cultural educational experiences of kura Kaupapa Māori differ significantly from the educational and environmental experiences offered at University. The participants’ narratives demonstrated that the clear sense of identity gained from the kura Kaupapa Māori context gave them the inner strength to cope with these differences. In addition to their strong sense of Māori identity, the main coping mechanisms that the students drew on, was the wealth of institutional knowledge that family members and role models provided of the university context as past students and current staff members. The benefits that these students experienced can be strengthened by building stronger relationships between Māori total immersion schools, the wider Māori community and universities ensuring that Māori total immersion students are able to access the academic and institutional knowledge they need to succeed. 
Furthermore, the thesis argues that the kura Kaupapa Māori movement can deliver more for their students if they do not shut out the Pākehā world but rather teach their students to walk between and within the two worlds. In order to better understand this balancing act, the lived experiences of immersion students requires more research, particularly as more and more kura graduates transition into Aotearoa New Zealand tertiary settings.

year: 2016