Present Worth Cost Research Articles

Optimal rehabilitation planning for aged water distribution mains considering cascading failures of interdependent infrastructure systems

Abstract Water distribution networks (WDNs) with other infrastructures constitute a complex and interdependent multi-utility system. Considering interdependencies between WDNs and other urban infrastructures, this work proposes WDN intervention planning using a dynamic multi-utility approach to tackle the challenges of pressure deficits and cascading failures by the decoupling of different infrastructure systems. For this purpose, the study develops reliability indices representing the hydraulic and decoupled statuses of WDNs with neighbor infrastructures; the hydraulic reliability represents the robustness of the network against the water pressure deficit, and decoupling reliability represents the extent to which WDN elements are decoupled from other assets elements. A multi-objective optimization algorithm is employed to develop rehabilitation strategies by introducing three approaches for WDN upgrade following a phased design and construction method. Evaluating intervention plans based on construction cost, reliability and cascade effects shows that, under budget limitation conditions, decoupling a WDN could significantly save the cascade cost such that 1% improvement in the decoupling reliability brings about 157.42 billion Rials cascade cost saving to asset managers. On the other hand, the decoupled network is weak against hydraulic reliability, which could make it by far less resilient network than the coupled network with around 75% hydraulic reliability difference.

ECONOMIC ROTATION OF VACHELLIA NILOTICA (KIKAR) AND EUCALYPTUS CAMALDULENSIS (SUFEIDA) IN PUNJAB, PAKISTAN

The economic rotation of two different tree species was calculated during 2020 in two different tehsils (sub-districts) namely Gujranwala and Khushab which are located in Punjab province of Pakistan. Vachellia is a common tree grown on the farmlands of Gujranwala while Eucalyptus is a common tree growing on the farmlands of Khushab. So that these two tree species were selected from two different tehsils of Punjab. Vachellia is grown at a rotation of 10 to 20 years while Eucalyptus is grown on 5 to 12 years rotation. For the evaluation of economic rotation of both tree species, net present worth and benefit cost ratio was calculated. 300 trees of both tree species were randomly selected from their respective tehsils. Different rotations of Eucalyptus were tested viz., 12 years rotation, 6 + 6 = 12 years, 8 + 4= 12 years and 4 + 8 = 12 years, while the total span (12 years) was kept same in all rotations. The total span was kept at 12 years because this tree is grown at a maximum rotation of 12 years on the farmlands. Similarly, different rotations were tested in case of Vachellianilotica viz., 10 years, 5 + 5 = 10 years and 6 + 4 = 10 years with the same total span of 10 years. In case of Eucalyptus, net present worth was found to be Rs. 4035.525, 4506.45, 4310.375 and 4379.175 at a rotation of 12, 6+6 = 12, 8+4=12 and 4+8 = 12 years, respectively. However, best rotation was found to be 6 + 6 = 12 years with highest net present worth. Similarly in case of Vachellia, net present worth was found to be Rs. 4844.532, 5155 and 5675.322 at a rotation of 10 years, 5 + 5 = 10 years and 6 + 4 = 10 years, respectively. rotation of 6 + 4 = 10 years was found to be best. It is recommended that farmers of Khushab should grow Eucalyptus trees at a rotation of 6 + 6 = 12 years. The farmers of Gujranwala are recommended to raise Vachellia trees on a rotation of six years followed by another short rotation of 4 years for more financial benefits.

Techno-economic optimization of wind energy based hydrogen refueling station case study Salalah city Oman

Clean energy resources will be used more for sustainability improvement and durable development. Efficient technologies of energy production, storage, and usage results in reduction of gas emissions and improvement of the world economy. Despite 30% of electricity being produced from wind energy, the connection of wind farms to medium and large-scale grid power systems is still leading to instability and intermittency problems. Therefore, the conversion of electrical energy generated from wind parks into green hydrogen consists of an exciting solution for advancing the development of green hydrogen production, and the clean transportation sector. This paper presents a techno-economic optimization of hydrogen production for refueling fuel cell vehicles, using wind energy resources. The paper analyses three configurations, standalone Wind-Park Hydrogen Refueling Station (WP-HRS) with backup batteries, WP-HRS with backup fuel cells, and grid-connected WP-HRS. The analysis of different configurations is based on the wind potential at the site, costs of different equipment, and hydrogen load. Therefore, the study aims to find the optimized capacity of wind turbines, electrolyzers, power converters, and storage tanks. The optimization results show that the WP-HRS connected to the grid has the lowest Present Worth Cost (PWC) of 6,500,000 €. Moreover, the Levelized Hydrogen Cost (LHC) of this solution was found to be 6.24 €/kg. This renewable energy system produces 80,000 kg of green hydrogen yearly.

Energy, Exergy, Economic, Environmental (4Es) comparative performance evaluation of dewpoint evaporative cooler configurations

The performance of different configurations of Maisotsenko (M-cycle) based dew point evaporative cooler is significantly effected by operating range in a certain climate. Moreover, the system's economic and environmental aspects are equally important for its viability. In the current study, experimentation is conducted to explore the impact of the wide range of operating parameters on performance. The experimental results are further utilized for 4E (energy, exergy, economic and environmental) analysis of counter and cross flow configurations analysis along with resource consumption. Results show that supply temperature increases around 70% and 78%, cooling capacity increase about 87% and 60%, and energy efficiency ratio decreased 13.7% and 25.5% at low to high operating range. The maximum and minimum exergy efficiency of counter and cross flow are 46%, 18.23%, and 52%, 21.58%, respectively. Furthermore, counter flow configuration consumes 39% and 2.7%, 24.65% and 35%, 21.4%, and 38% more water and electricity consumption at low, medium, and high operating conditions. The decrease in present worth cost at low to high-interest rates is around 31.8% for counter flow and 29.6% for cross flow at a high range of operating parameters. The counter flow system at 13% interest rate has 48%, 34.6%, and 28% more life cycle cost than cross flow. Around 59%–34% more net present value with 1.3 years and 1.96 years of payback period at the high range of operating parameters. Moreover, the counter and cross flow configurations produce 158 to 342.57 kgCO2/month and 153 to 329 kgCO2/month, respectively when operated at low to high operating parameters range.

Comparison between Variable and Constant Refrigerant Flow Air Conditioning Systems in Arid Climate: Life Cycle Cost Analysis and Energy Savings

All over the world, there is a call to encourage sustainable energy thinking and implementation. There is an urgent need to consider sustainable solutions in any design projects that are able to reduce energy consumption. In the heating, ventilation, and air conditioning field, the rise of the variable refrigerant flow systems has made big progress. This study presents a life cycle cost analysis to evaluate the economic feasibility of constant refrigerant flow (CRF), and in particular, the conventional ducted unit air conditioning system and the variable refrigerant flow (VRF) system by using detailed cooling load profiles, as well as initial, operating, and maintenance costs. Two operating hours scenarios are utilized and the present worth value technique for life cycle cost analysis is applied to an existing office building located in Qatar, which can be conditioned by CRF and VRF systems. The results indicate that, although the initial cost of the VRF system is higher than that of the CRF system by 23%, the present worth cost of the VRF system is much lower than that of the CRF system at the end of the lifetime due to lower operating costs. There is also a significant energy saving of 27% by using VRF compared to the CRF. The implementation of these results on a national scale will promote the use of sustainable energy technologies such as the VRF system.

Energy, economic, and environmental (3E) feasibility study of desiccant integrated multistage efficient indirect evaporative air conditioning system configurations in the subtropical climate

This paper presents the experimental-based performance evaluation of three different configurations of desiccant integrated direct/indirect evaporative cooling systems. These configurations include (1) Conventional desiccant cooling system with the direct evaporative cooler on process and regeneration sides (Configuration 1); (2) direct evaporative cooler on the process with indirect evaporative cooler (M-Cycle) on regeneration side (Configuration 2); and (3) indirect evaporative cooler (M-Cycle) on process and regeneration sides (Configuration 3). Each configuration is analyzed in terms of process air supply temperature, process air humidity ratio, thermal coefficient of performance (COPth), and energy efficiency ratio (EER). Based on energy, economic and environmental (3E) analysis subjected to an ambient temperature range of 31–40 °C, 18 g/kg ambient humidity and regeneration temperature of 70 °C; Maximum average value COPth of 0.49, 0.8, 1.7 and EER 3, 4.12, 7 were achieved by configuration 1, 2 and 3, respectively. Present worth cost of configuration 3 for 10 h/day operating time is 13% less as compared to a conventional system with a payback period (PBP) of 6.5 years. As compared to configuration 1, the CO2 emission is reduced by 32% and 38% for configuration 2 and configuration 3, respectively. Hence, the energetic, environmental, and economic evaluation revealed that configuration 3 is best amongst all three configurations in subtropical climate conditions.

Life-Cycle Cost Analysis (LCCA) comparison of pavements (Flexible, rigid and rigid-admixed with cow bone ASH)

Life Cycle Cost Analysis (LCCA) acts as a decision support tool in economic evaluation of cost (agency and user) during pavement type selection, maintenance and rehabilitation strategy. The Life cycle cost analysis was done using the Present worth of Cost method. Technical Recommendations for Highway (TRH) 12 (pavement rehabilitation investigation and design) analysis was used for calculating the agency cost which entailed the initial rehabilitation, maintenance, future and salvage cost. The LCCA analysis period for this study was taken as 40 years as the analysis period have to be sufficiently long to reflect long-term cost differences associated with reasonable design strategies. The result of the study shows that the present worth cost for the varying Pavement presents the options available for decision making. The result revealed that the initial cost of Rigid pavement is the highest followed by the initial cost of Rigid pavement with 15% CBA while flexible Pavement has the lowest initial cost. However, considering the result showing the present worth cost for the varying pavement types present worth cost of flexible pavement is the highest followed by Rigid pavement and Rigid pavement with 15% CBA has the lowest life cycle cost. The study recommended that Rigid pavement with 15% CBA should be considered because it gives the lowest life cycle cost and the initial cost is relatively low.

The assessment of technical -economic efficiency of Sequencing Batch Reactors in municipal wastewater treatment in developing countries

The Sequencing Batch Reactors (SBR) is a variation of activated sludge and has been wide applied in wastewater treatment since 1920s. The advantages of this technology are not only the high performance in low or varying flow patterns but also present worth cost for a long time. Therefore, the article evaluates the technical -economic efficiency of this technology in municipal wastewater treatment from combined sewerage system. Based on building and operation pilot SBR with process Nitrification/Denitrification and bio-film in municipal wastewater treatment plan for 1 months, the technical -economic efficiency has been determinates. Firstly, the efficiency removal pollutants is more stable and the quality of pilot’s effluence achieved Russian Standard about treated water. After that, the environmental damage has been decreased for 8 – 11 time, especially damage from nitrogen ammonia and nitrate. At least, the calculation from economic factors of SBR has been showed that the cost of treating 1 m3 wastewater than 0.5 USD when optimized this technology by process Nitrification/Denitrification and bio-film.

Assessing recurrence probability for Oso 2014 landslide in order to manage risk

ABSTRACTIn March 2014, a catastrophic landslide in Washington State destroyed a community and killed 43 people. An analysis of the available information using a new approach to manage risk when dealing with rare, high consequence hazards indicates that if the risk for another landslide is accepted, then the expected time between occurrences of massive landslides at this location is about 2000–3000 years, the mean occurrence rate tends to increase with time since the last occurrence, and the alternative of avoiding the risk is preferred if the present worth cost to avoid it (i.e. prevent development) for 100 years is less than about 1/6 the cost of another massive landslide.

Economic feasibility of solar power plants based on PV module with levelized cost analysis

In this study, the cost analysis of solar power system, where is located in Elazığ, Turkey is calculated according to levelized cost analysis method. In the economic feasibility studies carried out by the firms, many parameters such as interest rates, cost of money, detailed sunshine duration, monthly net profit-loss status in one year, cost of investment according to changing interest rates are not taken into consideration. All these parameters, which were not considered by the firms, have been calculated in this study. The payback period of investing in the solar power plant is calculated as 13 years, the payback period of it is calculated as an average of 6.6 years by the firms. The annual profit of a 1 MW solar energy plant is 89,467 US $. Present worth and annual capital cost of the solar power plant are calculated as 1,156,763 US $ and 1,181,875 US $, respectively. The capital cost flow of the investing in solar power plant is determined as 5.628 US $/h. When the results obtained from this study are evaluated in a general framework, the high interest rates in developing countries will have a negative effect on the investments in the solar power plants.

Dynamic optimization of synthesis, design and operation of marine energy systems

In order to cover the overall energy demands of a vessel (e.g. mechanical, electrical and thermal), energy systems onboard ships are required to produce energy of several forms while at the same time being completely autonomous and cost effective. Optimization of the ship’s energy system, as a whole, in terms of synthesis, design and operation, is nowadays an unavoidable aspect of the marine industry. Furthermore, once time dependencies (e.g. time-varying loads and weather conditions) are introduced, the optimization problem is imperatively characterized as dynamic and its complexity increases dramatically. This study is focused on the dynamic optimization of synthesis, design and operation of a marine energy system. The general method, based on differential-algebraic equation formalism combined with mixed-integer nonlinear programming, along with solution procedures is presented first. The three optimization levels (synthesis, design and operation) are tackled simultaneously, with no decomposition. The superconfiguration approach is followed for the synthesis optimization, while time-varying operational requirements with respect to weather conditions and loads are considered. The presentation of the general theory is followed by application examples. A nominal case as described by a particular weather profile and values of parameters is considered, and the optimization problem with minimization of the present worth cost as an objective function is stated and solved. The effect of crucial parameters such as fuel and capital costs on the optimum solution is studied. Also, the problem is solved with a different weather profile, thus revealing the effect of weather on the optimum solution.

Teaching life cycle assessment in environmental engineering: a disinfection case study for students

To help educators increase the extent and effectiveness of integrating sustainability into undergraduate education, a case study in life cycle assessment (LCA) is developed and presented using the context of disinfection of wastewater. Design and operating parameters are presented for three alternatives: chlorine/sulfur dioxide, ultraviolet (UV) light, and sodium hypochlorite/sodium sulfite. The case study includes student learning objectives, design assumptions, system boundaries, supporting calculation files, descriptions of LCA simulation scenarios, expected simulation results, and interpretation. LCA simulations, using the ISO methodology approach, are performed with varying assumptions about design flows, study duration, electricity fuel mixes, an alternative LCIA methodology, and weighting scenarios. Results are presented primarily at the midpoint level, and the effects of weighting are illustrated using a ternary plot. Life cycle costing is performed by calculating net present worth cost of construction materials and selected ongoing operation and maintenance costs. After interpreting simulation results, students should be able understand and apply several LCA skills including identifying significant impact categories, describing tradeoffs between different life stages, identifying “hot-spots” in the life cycles, illustrating the impacts and limitations of weighting, and observing differences across LCIA methodologies. Using the assumptions herein, chlorine disinfection results in larger initial impacts due to the larger basin required for hydraulic retention time (HRT), but operating impacts associated with electricity consumption cause the UV impacts to overtake those of the chlorine alternative. The results are sensitive to the LCIA method, the electricity grid’s fuel mix, and the electricity consumed per unit of wastewater disinfected. Finally, consideration of non-environmental and non-cost factors (risk, safety) provide students with an opportunity to reflect on broader societal impacts. Adaptable for various audiences and to provide differing levels of technical rigor, the case study should aid students in understanding and becoming proficient in performing LCA to facilitate life cycle thinking. It is the author’s hope that by providing a transparent, comprehensive LCA case study comparing engineering alternatives, educators can better integrate life cycle thinking and systems thinking into engineering curricula.

SENSITIVITY ANALYSIS ON FLEXIBLE ROAD PAVEMENT LIFE CYCLE COST MODEL

Sensitivity analysis is a tool used in the assessment of a model’s performance. This study examined the application of sensitivity analysis on a developed flexible pavement life cycle cost model using varying discount rate. The study area is Effurun, Uvwie Local Government Area of Delta State of Nigeria. In order to determine one of the vital geotechnical engineering properties (i.e. California Bearing Ratio) of the soil samples required for this study, soil samples were taken from the subgrade of the study area using the disturbed sampling method. The laboratory test was carried out at geotechnical laboratory in Warri and in accordance with AASTHO 1993 to determine the subgrade strength. Existing data such as maintenance records, vehicular traffic counts, material costs, discount rate and pavement design data were sourced from the Delta State Ministry of Works, Effurun. These acquired data and CBR results of 5% and 6% were used for the design of three competing flexible pavement systems and Bill of Engineering Measurements obtained. These were used for the evaluation of the Life-Cycle Costs (LCCs) using present worth cost (PWC) method; varying discount rates in MS Excel spread sheets for a design life of 20 years. Regression modeling of the three scenarios was done with sensitivity analysis carried out on the developed model. The project age was used as its independent variable, while discount rate is a secondary independent variable varied by ±4%, ±8% and ±12% of the initial discount rate of 5.4% applied with the accuracy of 95%. The coefficient of determination (R 2 ) for the Hot Rolled Asphalt (HRA), Interlocking Concrete Pavement Block (ICPB) and Do-nothing models are 0.97, 0.95 and 0.99 respectively indicating a robustness of the developed models. The graphs produced from the sensitivity analysis indicate a decrease in life cycle cost with increasing interest rate for the alternatives. These results are vital for the economic evaluation of flexible pavement and transportation systems. http://dx.doi.org/10.4314/njt.v35i2.7

Robust optimization to secure urban bulk water supply against extreme drought and uncertain climate change

Urban bulk water systems supply water with high reliability and, in the event of extreme drought, must avoid catastrophic economic and social collapse. In view of the deep uncertainty about future climate change, it is vital that robust solutions be found that secure urban bulk water systems against extreme drought. To tackle this challenge an approach was developed integrating: 1) a stochastic model of multi-site streamflow conditioned on future climate change scenarios; 2) Monte Carlo simulation of the urban bulk water system incorporated into a robust optimization framework and solved using a multi-objective evolutionary algorithm; and 3) a comprehensive decision space including operating rules, investment in new sources and source substitution and a drought contingency plan with multiple actions with increasingly severe economic and social impact. A case study demonstrated the feasibility of this approach for a complex urban bulk water supply system. The primary objective was to minimize the expected present worth cost arising from infrastructure investment, system operation and the social cost of “normal” and emergency restrictions. By introducing a second objective which minimizes either the difference in present worth cost between the driest and wettest future climate change scenarios or the present worth cost for driest climate scenario, the trade-off between efficiency and robustness was identified. The results show that a significant change in investment and operating strategy can occur when the decision maker expresses a stronger preference for robustness and that this depends on the adopted robustness measure. Moreover, solutions are not only impacted by the degree of uncertainty about future climate change but also by the stress imposed on the system and the range of available options.

Life Cycle Cost Analysis (Lcca) Delivery Model for an Urban Flexible Pavement

Pavement alternative evaluation is a key aspect in decision making process in transportation system planning, design and delivery. This study examined the Life-Cycle Cost Analysis (LCCA) model for flexible road pavement infrastructure delivery in a developing economy using 1.9 km urban road in Effurun Metropolis, Uvwie Local Government Area of Delta State of Nigeria as a case study. The overview of existing knowledge, the importance and evaluation of LCCA of pavement delivery is done. The Pavement delivery and design data used for this study, which were obtained from the Office of the Ministry of Works, Effurun, Delta State of Nigeria, included soil sub-grade CBR results, water content condition, soil type and grain size distribution, the reports of route investigation, vehicular traffic counts, and previous maintenance, material and market survey reports. The pavement design data previously used for the design and procurement of urban roads in the area were used for the design of three competing pavement alternatives models, viz: Hot Rolled Asphalt (HRA), Interlocking Concrete Block Pavement (ICBP) and a third; Do-nothing scenario pavement alternative. The Bill of Engineering Measurements and Evaluation (BEME) was developed for the designed alternative to compute their Life- Cycle Costs (LCCs) using present worth cost (PWC) method with varying interest rates in MS Excel software spread sheets for a design life of 20 years. Regression modeling for the three scenarios was done with computer software’s (SPSS and MS Excel) packages. The model’s data robustness was determined and found to be between 0.95-0.99. The model’s validity and sensitivity were also carried out. The study indicates a 43.8% cost savings with the ICBP alternative over the HRA option. The Do-nothing alternative is non–aesthetical and costliest due to the maintenance cost of reinstating the road structure. The models have significance value of less than 0.001(F) respectively. The developed LCCA template and model are applicable for investment studies and decision making as well as cost effectiveness assessment of pavement and bridge delivery.

Experimental based energy performance analysis and life cycle assessment for solar absorption cooling system at University of Californian, Merced

Traditional air conditioning and heating systems in buildings are fossil fuel based energy systems, which take the main responsible for the carbon emissions. In contrast, using solar energy for air conditioning becomes one of the promising approaches to reduce energy consumptions and negative environmental impacts from buildings. University of California, Merced built a test facility to investigate the technology: solar cooling. The solar system has 54m2 external compound parabolic concentrator (XCPC) solar collectors to drive a 23kW double-effect absorption chiller. This paper first provides the detailed energy performance analysis of the experiments conducted in August, 2012. The data collected from the experiments shows that the system could provide adequate cooling for a test facility between 11AM to 5PM in both sunny and cloudy days. The daily average collector efficiency is at the range of 36% to 39%. The average coefficient of performance (COP) of the LiBr absorption chiller is between 0.91 and 1.02 with an average of 1.0, and the daily solar COP is approximately at 0.374.In addition to the experimental investigation, a detailed life cycle economic and environmental assessment was also performed by comparing the solar systems to the conventional systems in two types of office buildings at three locations at California. Two different solar cooling system configurations were considered: (i) configuration 1 sizes the area of solar collectors and absorption chiller to meet the peak cooling demand, and uses natural gas as the only backup energy source; (ii) configuration 2 sizes the area of solar collectors and absorption chiller to meet half of the peak cooling demand, and uses natural gas as the backup energy source for the absorption chiller, while incorporates an electrical vapor compression chiller to meet the rest half of peak cooling demand. The annual performance predicts that the systems can achieve the annual solar fraction around 55–68%. And the configuration 2 achieves better life cycle economic and environmental performance than the configuration 1. Specifically, the configuration 2 can achieve lower present worth cost during the entire life span than the conventional systems. And both configuration 1 and 2 can reduce the life time carbon footprint by 35–70%.

MBR vs. CAS: capital and operating cost evaluation

Previous studies have investigated capital and operating cost comparisons between membrane bioreactors and conventional treatment technologies for particular treatment scenarios. This study expands on prior work with the development of an Excel and Biowin based tool to compare the capital and operating costs of equivalent size greenfield wastewater treatment facilities using membrane bioreactor (MBR) vs. conventional activated sludge (CAS) processes based on identical influent loading conditions, variable temperature and flow peaking factors, and varying levels of effluent treatment objectives. The resulting capital and operating cost tables developed using this tool indicate which system is most cost-effective for each scenario evaluated. The tool can also be used to easily compare the 20-year Present Worth cost impacts of changing input variables such as the cost of concrete, land, chemicals, or electricity.

A case study for influence of building thermal insulation on cooling load and air-conditioning system in the hot and humid regions

Ensuring the effective thermal insulation in regions, where the cooling requirement of building with respect to heating requirement is dominant, is very important from the aspect of energy economy. In this study, the influence of thermal insulation on the building cooling load and the cooling system in case of air-conditioning by an all-air central air-conditioning system was evaluated for a sample building located in Adana, based on the results of three different types of insulation (A, B and C-type buildings) according to the energy efficiency index defined in the Thermal Insulation Regulation used in Turkey. The operating costs of the air-conditioning system were calculated using cooling bin numbers. Life-cycle cost analysis was carried out utilizing the present-worth cost method. Results showed that both the initial and the operating costs of the air-conditioning system were reduced considerably for all three insulation thicknesses. However, the optimum results in view of economic measurements were obtained for a C-type building. The thickness of thermal insulation for the buildings in the southern Turkey should be determined according to the guidelines for a C-type building.

Economic feasibility of growing capsicum crop under drip irrigation in West Bengal, India

Drip irrigation system has been one of the technical means to improve water use efficiency. In India, this system is gaining popularity among fruit growers and in water scarced area but a substantial area is being covered annually under vegetables crops. One of the major concerns raised by farmers about this system is its economic viability. In present study, the economic viability of drip irrigation system for growing capsicum crop based on discounted cash flow technique (Net present worth and Benefit cost ratio) was explored. Eight irrigation treatments were laid under drip with and without plastic mulch. The irrigation levels were taken as 1, 0.8 and 0.6 of the crop evapotranspiration. The pan evaporation method was used for estimation of reference evapotranspiration and Water Balance Approach was used for irrigation scheduling. The average amount of water supplied under treatment VD (100% irrigation requirement supplied with drip) was found to be 415 mm for whole growing season of the crop. Similarly the amount of water was found to be 332 mm and 249 mm for the treatment 0.8VD (80% irrigation requirement supplied with drip) and 0.6VD (60% irrigation requirement supplied with drip) respectively. Highest yield was recorded in case of treatment VD + PM (100% irrigation requirement supplied with drip plus plastic mulch) followed by VD. Yield under treatments 0.8VD, 0.6VD, 0.8VD + PM and 0.6VD + PM were significant while treatments VD, VF and VF + PM were at par with the treatment VD + PM. Net Present Worth (NPW) was found to be positive for all the treatments. The highest NPW was obtained under treatment VD as Rs. 309,734.90 and lowest was in case of 0.6VD + PM as Rs. 144,172.24. The yield per mm of water used was reported to be at higher side as 35 in both the treatments VD and VD + PM. But the yield per mm of water used was found to be lowest as 18.07 and 19 in case of VF and VF + PM respectively.

Life-cycle cost analysis for constant-air-volume and variable-air-volume air-conditioning systems

This study presents a life-cycle cost analysis using detailed load profiles and initial and operating costs to evaluate the economic feasibilities of constant-air-volume (CAV) and variable-air-volume (VAV) air-conditioning systems. The present-worth cost method for life-cycle cost analysis is applied to a sample building located in Adana, Turkey which can be conditioned with CAV or VAV systems. In the analysis, two different uses of the building (as a school or as an office center), two different operating scenarios for air-conditioning system (scenario 1 and scenario 2) and two different economic measures (developed and developing economy) are considered. It is found, for all the cases considered, that although initial cost of the VAV system is higher than that of the CAV system, the present-worth cost of the VAV system is lower than that of the CAV system at the end of the lifetime due to lower fan-operating costs.