University of Moratuwa Research – Reports

Permanent URI for this communityhttp://192.248.9.226/handle/123/8848

Browse

Now showing 1 - 17 of 17

item: Article-Full-text
Building envelope performance index for commercial bl ilding energy conservation
Jayasuriya, JPW; Attalage, RA
The role of thermo-physical and geometrical characteristics of a building envelope that plays in the air-conditioning load of the commercial sector is highlighted. A standard methodology of quantifying a performance index for the building envelope is reviewed and upgraded orporating local climatic, material and architectural features. The methodology which is a trade-off between prescriptive and performance criteria can be easily used to form a basis for efficiency building code (EEBC) for Sri Lanka. The methodology is illustrated through a case study
item: SRC-Report
Energy conservation in commercial buildings by optimizing the start stop sequence of the air-conditioning plant
Attalage, RA; Jayasinghe, MTR; Fernando, TMD
Sri Lanka has a warm humid climatic condition in low altitudes since it is located close to the equator. In many commercial buildings located in low altitudes, airconditioning is used as a popular option for providing the thermal comfort. However, this option is causing a lot of problems in recent past due to the energy crisis faced by Sri Lanka. The continuous increase of consumers has shifted the energy generation from hydropower to fossil fuels. Due to the recent price hikes of the petroleum in the world market, the electricity tariff rates have also been increased substantially. Therefore the cost of air-conditioning has increased considerably. With this, there is a considerable interest to optimize the performance of the air-conditioning systems. So that energy usage could be minimized. The reduction of energy used for air-conditioning is not a straightforward task. This is because it is important to maintain the thermal comfort indoors at an acceptable level. Therefore, developing strategies to reduce the energy consumed for airconditioning is important which has to be achieved without compromising thermal comfort of the occupants. The feasibility of the adjusting starts stop sequence of the air-conditioning plants was investigated with the aid of computer simulations carried out for a ten-story building. The effect on thermal comfort was determined by using the Predicted Mean Vote (PMV) index. It was shown that the number of operating hours could be reduced without affecting the thermal comfort, especially towards the end of the office hours. Such saving could be extremely important for countries like Sri Lanka that is facing an energy crisis amid the need to increase the number of consumers. The significance of such energy savings is quantified in terms of the number of rural houses that could be provided electricity. It is shown that the energy saved by adjusting the start stop sequence of a ten-story building is sufficient meet the electricity demand in about fifty rural houses.
item: SRC-Report
Energy conservation in tea industry
Attalage, RA; Sugathapala, AGT
Tea has become the most popular refreshing drink all over the world because of its natural taste, since the ancient times. The quality and the taste are unmatched with any other drink in the universe. Production processes of tea have its own features to obtain the expected level of taste and flavor. For these processes a massive amount of electrical and thermal energy is required. From the beginning of the tea industry it plays a vital role in Sn Lankas' economy as it contributes a significant portion of the national GDP (Gross Domestic Product). In the recent times importance of this industry has drastically reduced due to various reasons. In this chapter the above-mentioned factors will be considered m detailed.
item:
Energy conservation in tea industry
Attalage, RA; Sugathapala, AGT
Tea has become the most popular refreshing drink all over the world because of its natural taste, since the ancient times. The quality and the taste are unmatched with any other drink in the universe. Production processes of tea have its own feature to obtain the expected level of taste and flavor. For these processes a massive amount of electrical and thermal energy is required. From the beginning of the tea industry it plays vital role in Sri Lankas' economy as it contributes a significant portion of the national GDP (Gross Domestic Product). In the recent times importance of this industry has drastically reduced due to various reasons. In this chapter the above-mentioned factors will be considered in detailed.
item: SRC-Report
Enhancement of output of solar panels by means of reflectors
Watugala, GK; Attalage, RA
The energy supply from the sun is truly enormous: on average, the earth’s surface receives about 1.2*1017W of solar power. This means that less than one hour enough energy is supplied to the earth to satisfy the entire energy demand of the human population over the whole year. Indeed, it the energy of sunlight assimilated by biological organisms over millions of years that has made possible the industrial growth as we know. Most of the other renewable means of power generation also depend on the sun as the primary source: hydroelectric, wind and wave power all have the same origin. Solar cells did not have to wait long to find application. The year 1958 witnessed the launch of Vanguard 1, the first satellite to use electricity from the sun. The technology has been developing ever since. Much interest in solar electricity appeared particularly in the wake of the oil crisis in the early seventies. Today, the direct conversion of light into electricity, or photovoltaic, is becoming accepted as an important form of power generation.
item: Article-Full-text
Minimisation of energy demand in buildings
Jayasinghe, MTR; Attalage, RA
The neutral temperatures for different locations in Sri Lanka have been established using actual climatic data. Based on these neutral temperatures, standard comfort zone for each of these locations have been identified on the psychrometric chart and their validation has been carried out using field measurements. These standard comfort zones have been then modified for two different internal air velocity levels and their validity too has been checked. This provides a method of extending the boundaries of these comfort zones thereby accommodating higher levels of dry bulb temperatures and humidities. This fact is utilised as the basis of minimising the energy demand in buildings either air-conditioned or not, by making use of combined modes at different internal air velocities
item: Article-Full-text
Minimisation of energy demand in buildings
Jayasinghe, MTR; Attalage, RA
The neutral temperatures for different locations in Sri Lanka have been established using actual climatic data. Based on these neutral temperatures, standard comfort zone for each of these locations have been identified on the psychrometric chart and their validation has been carried out using field measurements. These standard comfort zones have been then modified for two different internal air velocity levels and their validity too has been checked. This provides a method of extending the boundaries of these comfort zones thereby accommodating higher levels of dry bulb temperatures and humidities. This fact is utilised as the basis of minimising the energy demand in buildings either air-conditioned or not, by making use of combined modes at different internal air velocities
item: Article-Full-text
Passive concepts for improvement of thermal an visual comfort in houses in Sri Lanka
Jayawardane, AI; Jayasinghe, MTR; Attalage, RA
One of the primary requirements of houses constructed in hot humid climatic conditions such as those prevailing in Sri Lanka is that those should be thermally comfortable for the occupants throughout the day and around the year. Most of the single and two storey houses constructed in Sri Lanka have failed to fulfill this requirement. Therefore, a critical review was undertaken to develop passive concepts that can be incorporated in the future houses. It is shown with a detailed study that three storey houses can perform much better than single and two storey houses not only with respect to thermal comfort, but also with respect to visual comfort, functionality, minimisation of flash floods, creation of a desirable micro climate etc. It is also shown that the cost of three storey houses can be in the range of that of the single and two storey houses, when the traditional construction materials are used in an efficient manner. The use of these concepts for houses built in the future in Sri Lanka will be extremely important in order to minimise the electrical energy required for operation of houses; this will be quite useful since the electrical energy sources available for Sri Lanka are limited.
item: SRC-Report
Passive techniques for energy efficiency of buildings in Sri Lanka : research papers
(2002) Jayawardane, AI; Jayasinghe, MTR; Attalage, RA
The following research papers were published from the above-mentioned titled, 1). Passive concepts for improvement of thermal and visual comfort in house in Sri Lanka, 2). Minimisation of total ownership cost of residential buildings, 3). Concepts for sustainable residential developments for urban and sub-urban areas in Sri Lanka, 4). Orientation of roof and openings: their influence on indoor thermal comfort of single storey houses, 5). Quantification of the passive potential of free running three storey houses, 6). Thermal performance of free running three storey houses: an assessment through computer simulations, and 7). Thermal comfort in proposed three storey passive houses for warm humid climates.
item: SRC-Report
Performance analysis of table and pedestal fans
Attalage, RA; Sugathapala, AGT
Performances of pedestal and table fans were analysed through experimental measurements of the induced flow field (velocity distribution) and the power consumption by three different fan types (makes). A test rig was constructed to facilitate the measurement of axial flow velocities in the three dimensional space. In order to predict the jet pattern produced by the fan, axial velocity distributions on sufficient number of planes were measured. These data were used to calculate the jet diameter, flow rate, kinetic energy and the linear momentum of the flow. The power consumption and the angular speed of the rotor for each regulator setting were also taken. The velocity distributions measured on different planes from the rotor clearly illustrate the general characteristics of the flow generated by free flow fans, including the reverse flow near the rotor plane, jet entrainment and diffusion. As an example, in one situation the maximum flow rate becomes four times the flow rate at the rotor plane, which distance of seven rotor diameters from the fan.
item: Article-Full-text
Quantification of the thermal performance of free-running three-storey houses
Jayawardena, AI; Jayasinghe, MTR; Attalage, RA
This paper explores the possible means to adopt environmentally-friendly passive techniques to promote thermal comfort inside houses with the view of minimizing the use of energy-intensive active means such as fans. This could reduce the operating cost of houses, growth of demand for electricity in the domestic sector and adverse effects on the environment resulting from human settlement. A three-storey passive house that could be proposed on the basis of qualitative studies was selected for the quantification of its thermal behaviour, using DEROB-LTH computer program, varying the surface colour of the roof, walls and floors. The same house was again simulated after removal of its passive features such as shading devices and balcony roof, and addition of undesirable features such as west-facing windows. For all cases, the same set of probable internal loads were used. The results indicated that the indoor temperature of a functional space of a passive house can be lower as much as by 5°C than that of the same space of the same house containing features that are thermally undesirable. The results also show that, in a passive house, the indoor temperature can be maintained below the maximum outdoor temperature, which occurs around 2 p.m. This is a significant finding that guarantees benefits at both individual and national level if passive techniques are adopted by a sizable population of the country.
item: SRC-Report
Retrofitting of a R-12 based domestic refrigerator to run on R-134a
Attalage, RA; Perera, KKCK
With the discovery of R134a, which has a negligible Ozone depletion potential, ODP (R11 is listed as 1.0 on the scale) and at least hundred orders of magnitude less Global warming potential (GWP) compared to CFCs, resulted the phasing out of the use of Freon-12 refrigerant in domestic refrigerators. As a result, continuing use of large number of domestic refrigerators run on Freon-12 and purchased prior to the introduction of phasing out mechanisms by the Montreal Protocol could be difficult if not impossible. Because, due to the differences in thermo-physical properties of R134a and Freon-12, modifications or replacement of main devices such as the compressor, condenser, capillary tube of the refrigeration cycle and the use of a compatible lubricant are required. In the present study modifications to the capillary tube length is suggested as the possible modification to the existing system. This choice of modification was based on the cost effectiveness and the convenience. In short it is cheaper and convenient. First a safe procedure of recovering the Freon-12 and the lubricant from the existing refrigerator and cleaning and preparing the system for recharging with the new refrigerant R134a was established. Performance tests were carried out to ensure that the refrigerator could function properly with the new refrigerant and the new lubricant, which is ployol ester and to compare the energy consumption & Coefficient of Performance (COP). Upon ensuring the proper function of the refrigerator with the new refrigerant R134a and the new lubricant, tests were carried out to compare the energy consumption and COP of the refrigerator with different capillary tube lengths namely, 25%, 30% and 35% length increments. The test results suggests that the domestic refrigerator designed to run with Freon-12 can be retrofitted to run with R134a successfully, with 30% increase in capillary tube length.
item: SRC-Report
Socioeconomic and environmental impact of rural household energy supplies
Wijayatunga, PDC; Attalage, RA
Majority of the households in Sri Lanka, as in the case of many developing countries, is concentrated in the rural areas of the country. But unfortunately, very little attention has been paid until recently to analyse and address various issues associated with the rural energy supplies particularly those with regard to barriers to penetration of clean and convenient sources of energy. This paper presents the results and analysis of a study carried out through a sample study on the domestic energy supplies in the rural Sri Lanka with emphasis on cooking and lighting energy requirements. The paper has attempted to highlight policy issues associated with rural energy supplies and possible solutions to them in the context of the country's overall picture of energy sector.
item: SRC-Report
Socioeconomic impact of solar home systems in rural Sri Lanka
Wijayatunga, PDC; Attalage, RA
The use of solar photovoltaic systems of 25Wp to 50Wp (or frequently called as solar home systems) have been spreading fast in the rural areas of Sri Lanka as a source of energy used for domestic lighting, mainly due to the financial incentives provided by the donor agencies and aggressive marketing strategies of the SHS dealers in rural areas. This paper presents the outcome and the analysis of a study conducted with the objective of investigating the social, economic and the environmental impact of Solar Home Systems in the rural Sri Lanka. The study involved in conducting a survey of 125 households in the Uva province of Sri Lanka having Solar Home Systems, through personal visits. It was evident that the households are extremely satisfied with the technology that has replaced their kerosene lamps, which had been providing household lighting requirements. The quality of life in terms of activities such as longer study hours of children, longer TV watching hours for the family and lessening the risk of fatal kerosene lamp accidents, has improved with the introduction of the solar home systems. It is concluded that the large-scale penetration of the solar home systems in Sri Lanka has helped the rural communities both in terms of improved socioeconomic conditions and reduced adverse environmental impacts contrary to the belief that the financial burden of such systems imposed on the families outweigh the benefits. But when comparing the benefits of SHS over the extension of the national grid, the country needs to seriously examine its options for the areas presently targeted by the SHS dealers.
item: SRC-Report
Study of thrust areas and strategy for university - industry linkage strengthening
(2013-11-08) Attalage, RA
item: SRC-Report
Study of thrust areas and strategy for University-industry linkage strengthening
Attalage, RA; Galappaththi, UIK
The link between the university and the industry is probably the most effective tool that is of mutual benefit to both parties for achieving a common goal. The university from one side can play a vital role in applying its knowledge & skills in innovation and in solving problems of value to the industry enabling them to relate more realistically to the needs of the industry and also to use back in the teaching program. The industry on the other side could benefit from the knowledge & skills of the university in order to maintain their competitive edge in the business world. The university-industry linkage would implicitly reflect most needed financial gains to both parties. The major objective of this report is to discuss the nature and scope of present university industry relationship in Sri Lanka, preliminary identification of important thrust areas in line with Government policies & priorities where university-industry could play a complementary effective role in view of local technological development and finally propose a strategy to strengthen present university focusing the department level in the faculty of engineering of UOM. A preliminary survey was carried out to study and investigate present status of university-industry linkage, to study government current industrial development plan, to identify targeted trust areas for future development in line with government plan, to recognize the main needs and come up with a strategy to strengthen university industry linkage in Sri Lanka.
item: Article-Full-text
Thermal performance of free-running three-storey houses: an assessment through computer simulations
Jayasinghe, MTR; Attalage, RA; Jayawardena, AI
Sri Lanka is presently facing a serious energy crisis due to continuous increase in energy demand annually. One of the solutions for this is energy conservation for which houses are a good candidate. The need for using active means such as fans and air-conditioning can be minimized by planning the houses with desirable passive features. In order to determine the passive performance, computer simulations were carried out for two houses with and without passive elements. A comparison of similar volumes in these two houses indicated that it is possible for the indoor temperature of certain type of volumes to rise about 5°C above the maximum outdoor temperature when passive elements are ignored.

Browse

Browsing University of Moratuwa Research – Reports by Author "Attalage, RA"