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Industrial refrigeration equipment companies are continuously looking for ways to optimise the design of chilling and freezing tunnels in order to minimise food quality loss and increase the energy efficiency of the equipment. However, possibilities for dedicated experimental tests of the industrial operations are limited due to a large amount of food product involved while the number of design variables to be considered is high. A cost-effective alternative to experiments is numerical modelling. The main goal of this research was to simulate heat transfer of packaged food products in a chilling and freezing tunnel. Computational fluid dynamics (CFD) models were developed to improve prediction in industrial cheese chilling and chicken freezing. The industrial cheese chilling model was developed based on six blocks of agar that mimic the product arrangement and airflow pattern of a cheese chiller; while the chicken freezing model represents the first case of a CFD freezing model where the geometry was derived empirically via computed tomography scan data. The model predictions were validated by experimental temperature histories generated as part of the study. Once validated, the model was used to investigate the cooling heterogeneity and the effect of different operating conditions on the processing time. In addition to the CFD model, a simple heat transfer simulation based on the one-dimensional finite difference method was developed for industrial users. Thermal property models in the literature were also reviewed to propose the most suitable choice for thermal processing calculations.

Invasive species are one of the biggest threats to development and well-being in the Pacific. They have wide-ranging impacts on economies, the environment, and societies; in addition to causing USD $1.4 trillion of losses each year. Invasive species are also the primary cause of biodiversity loss on islands which could significantly affect the ecosystem services which Pacific Islanders depend on. Every year New Zealand spends NZD $500 million on biosecurity, and Australia has spent AUD $175 million on a single eradication project. In comparison, in the Pacific there are only six people working fulltime on invasive species issues at a regional level and there is limited funding available. This thesis assesses the role of four New Zealand agencies that assist with invasive species management in the Pacific: the International Development Group of the Ministry of Foreign Affairs, the Biosecurity New Zealand division of the Ministry of Agriculture and Forestry, the Department of Conservation, and Landcare Research. Together these agencies provide funding, build capacity, offer technical advice, and occasionally implement projects. While there are important gains to New Zealand in assisting the Pacific with invasive species management, such as a reduced biosecurity threat and learning opportunities for staff, the desire to help the region for its own sake is a major driver. Suggestions for future improvement include having more information on the economic impacts of invasive species in the Pacific, increased coordination between donors, and including invasive species measures in regional trade agreements. It is hoped that New Zealand will continue to play its critical leadership role in invasive species management in the region.

A dynamic modelling methodology has been developed for the computer simulation of industrial refrigeration systems. A computer program, RefSim, has been developed which embodies the new methodology. RefSim contains a total of 33 separate models - 11 derived from existing models, six which are substantially enhanced and 16 which are new. In general, these models were derived from thermal considerations and ignored the effect of hydrodynamic processes in the refrigeration circuit. Models can be dynamically linked together as specified by the input data in order to simulate a complete plant. The program includes a set of simulation utilities which reduce the amount of work required to develop models. The object-oriented features of inheritance, encapsulation and polymorphism are used extensively. Substantial model development was carried out to achieve accurate predictions of the heat release profile during chilling and freezing of food product as product cooling makes the greatest contribution to both mean and peak heat loads in many industrial refrigeration plants. The new ordinary differential equation (ODE) model was tested against finite difference (FD) calculations for a range of product shapes and Biot numbers. The ODE model predicted to within ±10% of the FD calculation during almost all of the cooling process under the test conditions. The ODE model required several orders of magnitude less computation than FD while being capable of extension to shapes that could not be handled by FD. To test the new ODE model against experimental data, a differential air temperature method to measure the cooling food product heat load profile was developed. Both the FD and ODE methods predicted the heat load profile of freezing meat cartons to within the experimental margin for error (±10%). The ODE model also predicted the heat load profile of freezing lamb carcasses to a similar level of accuracy. Three refrigeration plants (a laboratory water chiller, a 18500 lamb per day