title: The integration of heat pumps with biomass boiler flue gas for generating hot water

authors: Muldoon, Catherine

subjects: Biomass boiler

abstract: Achieving the goal of net zero greenhouse gases by 2050 requires reducing demand and switching from fossil fuels to renewables. Process heat in New Zealand is a significant source of greenhouse gas emissions. Transitioning to biomass boilers could lower emissions and offer opportunities for waste heat recovery by integrating heat pumps with the flue gas.
This thesis evaluates heat pump integration for hot water production, supplying low temperature process heat. Using an industrial case study, a boiler model is developed and confirmed against industrial measurements. Flue gas composition is modelled to determine temperature-enthalpy profiles, and therefore the heat available for recovery and upgrade. Combustion is modelled for different biomass fuels and varying flue gas oxygen levels. The higher moisture fuels showed increased availability of heat for utilisation, which decreased as flue gas oxygen levels increased.
Three heat pump cycles are explored to maximise efficiency. Refrigerant selection is considered with respect to environmental factors and thermodynamic suitability. Using a basic cycle heat pump the three most promising refrigerants, ammonia, propane and cyclopropane, were identified and considered in more detail for the industrial case. Subcooling improved efficiency and should be maximised. An internal heat exchanger also improves efficiency and reliability and should be considered. Two zeotropic mixtures were investigated to take advantage of the temperature glide. The propane-pentane (50wt%-50wt%) blend matched the temperature profile more closely and provided increases in COP.
To make the most of the latent heat in the flue gas, the evaporator temperature must be much lower than the dew point. However, absorbing heat from low source temperatures results in lower COPs, but higher volumes of hot water generated.

text: The integration of heat pumps with biomass boiler flue gas for generating hot water Achieving the goal of net zero greenhouse gases by 2050 requires reducing demand and switching from fossil fuels to renewables. Process heat in New Zealand is a significant source of greenhouse gas emissions. Transitioning to biomass boilers could lower emissions and offer opportunities for waste heat recovery by integrating heat pumps with the flue gas.
This thesis evaluates heat pump integration for hot water production, supplying low temperature process heat. Using an industrial case study, a boiler model is developed and confirmed against industrial measurements. Flue gas composition is modelled to determine temperature-enthalpy profiles, and therefore the heat available for recovery and upgrade. Combustion is modelled for different biomass fuels and varying flue gas oxygen levels. The higher moisture fuels showed increased availability of heat for utilisation, which decreased as flue gas oxygen levels increased.
Three heat pump cycles are explored to maximise efficiency. Refrigerant selection is considered with respect to environmental factors and thermodynamic suitability. Using a basic cycle heat pump the three most promising refrigerants, ammonia, propane and cyclopropane, were identified and considered in more detail for the industrial case. Subcooling improved efficiency and should be maximised. An internal heat exchanger also improves efficiency and reliability and should be considered. Two zeotropic mixtures were investigated to take advantage of the temperature glide. The propane-pentane (50wt%-50wt%) blend matched the temperature profile more closely and provided increases in COP.
To make the most of the latent heat in the flue gas, the evaporator temperature must be much lower than the dew point. However, absorbing heat from low source temperatures results in lower COPs, but higher volumes of hot water generated.

year: 2024

title: The Effects of Delayed Positive Reinforcement on Learning in Dogs

authors: Browne, Clare Melody

abstract: Domestic dogs (Canis familiaris) have lived closely with humans for thousands of years. Successful dog training is important for dogs to fulfil the many roles that they play within human societies, and to aid good human-dog relationships and thus the welfare of both parties. The overall aim of this thesis was to investigate the interactions that take place between humans and dogs during training, with a particular focus on the timing of positive reinforcement delivery.
The first two studies examined sources of dog training information. Dog owners and trainers rated their own personal experiences as being the most valuable source of dog training information, followed closely by free or low-cost resources such as books, discussions with other owners or trainers, and the Internet. The second study examined the content of five popular dog training books, and found that some of the information on aspects of learning theory and human-given cues presented in these books was supported by academic literature; however, inconsistencies were found across the books. Not all of the books contained enough information to enable readers to replicate their training advice.
The third study in this thesis used video observations of owners and their dogs at dog training clubs to investigate the timing of positive reinforcement during training. Dogs failed to respond to 44.20% of their owners’ commands. Typically, conditioned reinforcement (e.g., verbal praise) was delivered first (average delay was 0.62 s), followed by unconditioned reinforcement (average delay was 0.98 s). This suggests that delayed reinforcement is commonplace in real-life dog training.
Study four examined the effects of delays on dogs’ learning in a laboratory setting. When unconditioned positive reinforcement was delayed by 1 s, only 25.00% of dogs learned the task, whereas 60.00% of dogs who received immediate unconditioned reinforcement learned. Forty percent of dogs who received immediate conditioned reinforcement and unconditioned reinforcement delayed by 1 s, learned the task. These findings show that dogs’ learning is affected negatively by delayed positive reinforcement.
The final study aimed to determine how dogs are able to learn in everyday dog training situations if delayed positive reinforcement is both a common occurrence and detrimental to dogs’ learning. Observations of owners training their dogs revealed that owners gave signals in the form of body movements such as hand gestures prior to providing any intentional feedback (e.g., verbal praise) to their dogs in 75.26% of trials (average delay was 0.31 s), which may bridge the temporal gap between dogs’ responses and delayed reinforcement, thus aiding dogs’ learning.
Overall findings from this thesis suggest that delays to positive reinforcement are detrimental to dogs’ learning. Advice to dog owners and trainers should emphasise speed and consistency when delivering feedback to dogs.

text: The Effects of Delayed Positive Reinforcement on Learning in Dogs Domestic dogs (Canis familiaris) have lived closely with humans for thousands of years. Successful dog training is important for dogs to fulfil the many roles that they play within human societies, and to aid good human-dog relationships and thus the welfare of both parties. The overall aim of this thesis was to investigate the interactions that take place between humans and dogs during training, with a particular focus on the timing of positive reinforcement delivery.
The first two studies examined sources of dog training information. Dog owners and trainers rated their own personal experiences as being the most valuable source of dog training information, followed closely by free or low-cost resources such as books, discussions with other owners or trainers, and the Internet. The second study examined the content of five popular dog training books, and found that some of the information on aspects of learning theory and human-given cues presented in these books was supported by academic literature; however, inconsistencies were found across the books. Not all of the books contained enough information to enable readers to replicate their training advice.
The third study in this thesis used video observations of owners and their dogs at dog training clubs to investigate the timing of positive reinforcement during training. Dogs failed to respond to 44.20% of their owners’ commands. Typically, conditioned reinforcement (e.g., verbal praise) was delivered first (average delay was 0.62 s), followed by unconditioned reinforcement (average delay was 0.98 s). This suggests that delayed reinforcement is commonplace in real-life dog training.
Study four examined the effects of delays on dogs’ learning in a laboratory setting. When unconditioned positive reinforcement was delayed by 1 s, only 25.00% of dogs learned the task, whereas 60.00% of dogs who received immediate unconditioned reinforcement learned. Forty percent of dogs who received immediate conditioned reinforcement and unconditioned reinforcement delayed by 1 s, learned the task. These findings show that dogs’ learning is affected negatively by delayed positive reinforcement.
The final study aimed to determine how dogs are able to learn in everyday dog training situations if delayed positive reinforcement is both a common occurrence and detrimental to dogs’ learning. Observations of owners training their dogs revealed that owners gave signals in the form of body movements such as hand gestures prior to providing any intentional feedback (e.g., verbal praise) to their dogs in 75.26% of trials (average delay was 0.31 s), which may bridge the temporal gap between dogs’ responses and delayed reinforcement, thus aiding dogs’ learning.
Overall findings from this thesis suggest that delays to positive reinforcement are detrimental to dogs’ learning. Advice to dog owners and trainers should emphasise speed and consistency when delivering feedback to dogs.

year: 2015

title: An evaluation of the Raukawa Health Services Kaumatua Mirimiri Programme

authors: Gregg, Lisa

subjects: Maori

abstract: The Kaumatua Mirimiri Programme was funded as a Service to Improve Access project under a contract which ran from 1st September 2004 to 30th June 2005. Its aim was to provide a “culturally based treatment and recovery programme to restore the health and independence” of people aged 40 years and over (Pinnacle Group Ltd, 2004a, p.1). However, as the service specification in the contract made clear, the programme was not designed be exclusive: it has attracted younger as well as older people, non-Māori as well as Māori, and people seeking help for a wide range of ailments and pain.

text: An evaluation of the Raukawa Health Services Kaumatua Mirimiri Programme The Kaumatua Mirimiri Programme was funded as a Service to Improve Access project under a contract which ran from 1st September 2004 to 30th June 2005. Its aim was to provide a “culturally based treatment and recovery programme to restore the health and independence” of people aged 40 years and over (Pinnacle Group Ltd, 2004a, p.1). However, as the service specification in the contract made clear, the programme was not designed be exclusive: it has attracted younger as well as older people, non-Māori as well as Māori, and people seeking help for a wide range of ailments and pain.

year: 2006-03