Development of a triple stage heat transformer for the recycling of low temperature heat energy

Absorption heat transformers are thermodynamic systems which are capable of recycling industrial waste heat energy by increasing its temperature. Triple stage heat transformers (TAHTs) can increase the temperature of this waste heat by up to approximately 145˚C. The principle factors influencing the thermodynamic performance of a TAHT and general points of operating optima were identified using a multivariate statistical analysis, prior to using heat exchange network modelling techniques to dissect the design of the TAHT and systematically reassemble it in order to minimise internal exergy destruction within the unit. This enabled first and second law efficiency improvements of up to 18.8% and 31.5% respectively to be achieved compared to conventional TAHT designs. The economic feasibility of such a thermodynamically optimised cycle was investigated by applying it to an oil refinery in Ireland, demonstrating that in general the capital cost of a TAHT makes it difficult to achieve acceptable rates of return. Decreasing the TAHT's capital cost may be achieved by redesigning its individual pieces of equipment and reducing their size. The potential benefits of using a bubble column absorber were therefore investigated in this thesis. An experimental bubble column was constructed and used to track the collapse of steam bubbles being absorbed into a hotter lithium bromide salt solution. Extremely high mass transfer coefficients of approximately 0.0012m/s were observed, showing significant improvements over previously investigated absorbers. Two separate models were developed, namely a combined heat and mass transfer model describing the rate of collapse of the bubbles, and a stochastic model describing the hydrodynamic motion of the collapsing vapour bubbles taking into consideration random fluctuations observed in the experimental data. Both models showed good agreement with the collected data, and demonstrated that the difference between the solution's temperature and its boiling temperature is the primary factor influencing the absorber's performance.

Development and psychometric evaluation of the spirituality instrument (SpI-27) in a sample of people with chronic illness

Background: Spirituality is fundamental to all human beings, existing within a person, and developing until death. This research sought to operationalise spirituality in a sample of individuals with chronic illness. A review of the conceptual literature identified three dimensions of spirituality: connectedness, transcendence, and meaning in life. A review of the empirical literature identified one instrument that measures the three dimensions together. Yet, recent appraisals of this instrument highlighted issues with item formulation and limited evidence of reliability and validity. Aim: The aim of this research was to develop a theoretically-grounded instrument to measure spirituality – the Spirituality Instrument-27 (SpI-27). A secondary aim was to psychometrically evaluate this instrument in a sample of individuals with chronic illness (n=249). Methods: A two-phase design was adopted. Phase one consisted of the development of the SpI-27 based on item generation from a concept analysis, a literature review, and an instrument appraisal. The second phase established the psychometric properties of the instrument and included: a qualitative descriptive design to establish content validity; a pilot study to evaluate the mode of administration; and a descriptive correlational design to assess the instrument’s reliability and validity. Data were analysed using SPSS (Version 18). Results: Results of exploratory factor analysis concluded a final five-factor solution with 27 items. These five factors were labelled: Connectedness with Others, Self-Transcendence, Self-Cognisance, Conservationism, and Connectedness with a Higher Power. Cronbach’s alpha coefficients ranged from 0.823 to 0.911 for the five factors, and 0.904 for the overall scale, indicating high internal consistency. Paired-sample t-tests, intra-class correlations, and weighted kappa values supported the temporal stability of the instrument over 2 weeks. A significant positive correlation was found between the SpI-27 and the Spirituality Index of Well-Being, providing evidence for convergent validity. Conclusion: This research addresses a call for a theoretically-grounded instrument to measure spirituality.

Caregiver burden and resilience among Malaysian caregivers of individuals with severe mental illness

Little research has focused on caregiver burden experienced by Malaysian caregivers of individuals with mental illness, despite the fact that data in the Asian region shows almost threequarter of patients with mental illness live with family members. The aim of this research was to examine the levels of caregiver burden and resilience of caregivers of individuals with severe mental illness and to determine the influencing factors on caregiver burden. A quantitative, cross sectional, correlational design was used to measure burden and resilience and to explore the relationship between demographic variables, caregiver stressors, resilience and caregiver burden. This study was guided by the model of Carer Stress and Burden. Data collection was conducted over two months in summer 2014. A self-administered questionnaire that consisted of four sections measuring demographic data, primary stressors, caregiver burden and resilience was used to collect data. Two hundred and one caregivers of individuals with mental illness attending Psychiatric Outpatient Clinics in Malaysia were recruited. Samples were selected using non-probability, consecutive sampling. Factors that were found to be significantly associated with caregiver burden were caregivers’ age, gender, ethnic group, employment status, having a medical condition and current health status. The primary stressors found to be significantly associated with caregiver burden include the time spent for caregiving tasks, unavailability of support with caregiving tasks, lack of emotional support and patients’ behavioural disturbances. In addition, it was found that caregivers who were less resilient reported a higher level of caregiver burden. Findings from hierarchical multiple regression indicated that caregivers’ marital status, current health status, time spent for caregiving and resilience predicted caregiver burden. This research provides insight into caregiver burden among caregivers of individuals with mental illness in Malaysia. It highlights the important factors associated with caregiver burden and the significant role of resilience in reducing caregiver burden.