Lu Aye

Computer simulation of a downdraft wood gasifier for tea drying

Abstract A gasifier has been fabricated in Sri Lanka for the tea industry, but there is a lack of knowledge of the effect of certain key operating parameters and design features on its performance. Experimental testing of the design under various conditions has produced data that has then been used to calibrate a computer program, developed to investigate the impact of those parameters and features on conversion efficiency. The program consists of two sub-models of the pyrolysis and gasification zones, respectively. The pyrolysis sub-model has been used to determine the maximum temperature and the composition of the gas entering the gasification zone. The gasification zone sub-model has been calibrated using data gathered from the experiments. It was found that a wood chip size of 3– 5 cm with a moisture content below 15% (d.b.) should be used in this gasifier. Feed material with a fixed carbon content of higher than 30% and heat losses of more than 15% should be avoided. For the above parameters, the gasification zone should be 33 cm long to achieve an acceptable conversion efficiency.

Solar heat pump systems for domestic hot water

Vapour compression heat pumps can upgrade ambient heat sources to match the desired heating load temperature. They can offer considerable increase in operational energy efficiency compared to current water heating systems. Solar heat pumps collect energy not only from solar radiation but also from the ambient air. They can operate even at night or in totally overcast conditions. Since the evaporator/collector operates at temperatures lower than ambient air temperature it does not need glazing or a selective coating to prevent losses. Currently, however, they are not used much at all in domestic or commercial water heating systems. In this paper comparison is made of a conventional solar hot water system, a conventional air source heat pump hot water system and a solar heat pump water heating system based on various capital city locations in Australia. A summary is given of specific electricity consumption, initial and operating costs, and greenhouse gas generation of the three systems dealt with in this paper. The ultimate choice of unit for a particular location will depend heavily on the solar radiation, climate and the local price paid for electricity to drive or boost the unit chosen.

An ice thermal storage computer model

Abstract In hot humid countries such as Thailand, air conditioning plant is installed in most commercial and industrial buildings. A conventional air conditioning system, which is normally operated when cooling is required, is the most favored option. Ice thermal storage on a large scale, used to provide a cool reservoir for use in peak periods, is however an attractive financial option for large buildings to supply coolness. There are two means of operating ice thermal storage systems, namely full storage and partial storage. In this paper, a computer model has been developed in order to compare energy use in conventional air cooling systems and ice thermal storage systems. Under Thailand electricity tariff rates, the results from the simulations show that the full ice thermal storage can save up to 55% of the electricity cost required for cooling per month when compared with the conventional system. It is also found that using full storage option can reduce the total energy consumption by 5% for the selected building.

Natural working fluids for solar-boosted heat pumps

The option of using natural working fluids as a substitute of R-22 for solar-boosted heat pumps depends not only upon thermal performance and hazardous rating but also on potential impacts on the environment. This paper presents the comparative assessment of natural working fluids with R-22 in terms of their characteristics and thermophysical properties, and thermal performance. Some justification is given for using natural working fluids in a solar boosted heat pump water heater. The results show that R-744 is not suitable for solar-boosted heat pumps because of its low critical temperature and high operational pressures. On the other hand, R-717 seems to be a more appropriate substitute in terms of operational parameters and overall performance. However, major changes in the heat pumps are required. R-290 and R-1270 are identified as candidates for direct drop-in substitutes for R-22.

Environmentally sustainable development: a life-cycle costing approach for a commercial office building in Melbourne, Australia

A range of property and construction options is analysed using standard life-cycle costing methodology. The options are to renovate the existing building, buy an alternative building and renovate, and buy a development site and construct a new building. The do-nothing option and a hypothetical option to construct a new building on an ideal site are analysed as benchmarks. The results show that the optimum option is to buy a suitable site and construct a new building and that the least sustainable option, in the case study, is to stay in the existing property and renovate the building. Although staying in the existing building and doing nothing carries the lowest financial cost, energy consumption and greenhouse emissions are significantly worse than for the alternative options.

Planning Healthy, Liveable and Sustainable Cities: How Can Indicators Inform Policy?

Creating ‘liveable’ communities that are healthy and sustainable is an aspiration of policymakers in Australia and overseas. Indicators are being used at the national, state and local level to compare the liveability of cities and regions. Yet, there are challenges in the adoption of such indicators. Planning scholars see a challenge in creating indicators that measure something publicly valued, while public health researchers are concerned about scant systemic research on relationships between policies, the built environment, and health and well-being. This article provides an overview of liveability indicators used to date in Australia and internationally. It then outlines the results of consultations with Melbourne-based academics and decision-makers, on how to increase their utility and support the creation of healthy, liveable and sustainable cities.

Electrical and engine driven heat pumps for effective utilisation of renewable energy resources

Much of the energy used for domestic, commercial and industrial purposes is to provide efficient and effective heating of conditioned spaces and for specialist niche applications in process heat systems. Vapour compression heat pumps driven by electric motors or engines provide the real capability of upgrading low temperature sources of ambient and waste heat to match the desired load temperatures in such heating applications. Major source of ambient heat stem from the storage of solar energy in the ground, in lakes and rivers, and in atmospheric air. Heat pumps can therefore be used to effectively harness indirectly the daily solar radiation input. In addition many industries have major sources of waste low grade heat in the form of air or water discharged from the industrial process heat stream. Heat pumps are generally formally classified therefore as air source, ground source or water source units although there has also been considerable interest recently in hybrid units combining the attributes of two or more of these specific types mentioned above.

More than a survey: an interdisciplinary post-occupancy tracking of BER schools

In February 2009, the Australian Government announced the

Economic risk analysis for sustainable urban development: validation of framework and decision support technique

16.2b Building the Education Revolution (BER) as part of an economic stimulus package. In the context of a global financial crisis, the Government called for ‘shovel ready’ projects requiring state education departments to develop template designs to speed the delivery process. Three years later, new facilities have been completed in over 1100 government schools in Victoria (DEECD, 2012). This article outlines research by an interdisciplinary team to track the early occupation of a template design used in Victoria. The design template was unusual: it enabled schools to continue using traditional classroom teaching or to slide open walls to form larger neighbourhoods suitable for team teaching. Our research linked different methodological frameworks to undertake post-occupancy evaluation (POE) of the new spaces. POE strategies are often driven by construction and project management perspectives rather than focus on organizational issues and user behaviour.

Energy Optimized Wireless Sensor Network for Monitoring inside Buildings: Theoretical Model and Experimental Analysis

AbstractSustainable urban development requires detailed assessment of economic, environmental and social impacts borne by major stakeholders. A framework to address these complex issues underpinning sustainable urban development is proposed to aid decision making in the face of uncertainties. An analytical approach is developed as a tool to assist decision makers by using an engineering approach, risk-based cost-benefit analysis model that encompasses concepts from “Life Cycle Costing”, “Engineering Reliability Analysis” and “Risk Management”. It aims to rank design options based on model outputs, such as rate of return, probability of loss and value at risk. This study presents the logic of this approach and tests the framework using a synthetic project formulated around the economic perspective of an investor in considering the implementation of various desalination plant technologies. Two alternative desalination plants were evaluated based on a collective of project information, and the results showed...