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This paper analyzes the optimal Re for the steady, laminar, fully developed forced convection in a helical coiled tube with constant wall heat flux based on minimal entropy generation principle. Two working fluids, water and air, are considered. It is found that the entropy generation distributions are relatively insensitive to coil pitch, λ. Through the entropy generation analysis for cases of coil...
In this paper, we conduct a cross-country analysis of energy consumption and energy efficiency for the dairy industry in four European countries. Changes in energy efficiency were monitored in two different ways. One way is to look at the energy use by tonne of milk processed by dairies (EEIp1). Another way is by comparing the actual energy use with the energy that would have been used if no changes...
Procedures for sizing and optimizing the structure of solar collection systems are proposed. Four economical indices, including net present value and internal return rate, are given as examples of objective functions. Three solar energy applications were considered. A rather involved but still simple flat-plate solar collector model is used in calculations. The implementation was made for a specific...
Exergy is used as a common currency to assess and compare the reservoirs of theoretically extractable work we call energy resources. Resources consist of matter or energy with properties different from the predominant conditions in the environment. These differences can be classified as physical, chemical, or nuclear exergy. This paper identifies the primary exergy reservoirs that supply exergy to...
In this paper, we have used energy and physical production data to develop energy efficiency indicators for the meat industry of four European countries for the last 15 years. Our results show a significant increase in the energy use per tonne of product in all countries (between 14% and 48%). In order to understand the drivers behind the trends, factors such as the share of frozen products, the share...
The integration of different energy systems, e.g., industrial and municipal, is potentially important for the efficient utilization of energy. It is important that the tools for analysing this type of integration can handle the energy systems on different levels, e.g., regional, site, plant and process levels. In this work, a framework for investigating the cost-efficient integration of large-scale...
The small scale industry (SSI) is an important component of Indian economy and a majority of SSI units tend to exist in geographical clusters. Energy efficiency is crucial for the survival and growth of energy intensive SSI clusters, not only to improve their competitiveness through cost reduction but also to minimize adverse environmental impacts. However, this is easier said than done due to the...
This paper studies how to improve the capacity of the combined cycle (CC) power plant which has been operated for 8 years. The most popular way is to lower intake air temperature to around 15°C (ISO) and 100% RH before entering the air compressor of a gas turbine (GT). Thailand has 3 seasons: winter, summer and rainy season. According to 2003 Bangkok monthly weather data, all year ambient temperature...
The thermodynamics of a solar thermochemical cycle for the capture of CO 2 from air are analyzed. The cycle encompasses 3 reactors: an aerosol-type carbonator for capturing CO 2 from air using a spray of Ca(OH) 2 aqueous solution, a solar calciner for thermally decomposing CaCO 3 into CaO using concentrated solar energy, and a conventional slaker for regenerating Ca(OH)...
This paper presents a simulation code for the thermal power plant AVV1, located in Copenhagen, Denmark, in response to the challenge launched at the ECOS 2003 congress. The simulation program was specially created for this contest, including the calculation of the thermodynamic properties of water, as based on IAPWS97. Every component of the plant is modeled through mass and energy balance equations,...
The electricity tariffs in Oman are subsidized and are based on a cost accounting approach and do not reflect the true cost incurred in generating, transmitting and distributing a kilowatt-hour of electricity at the consumer end. This paper presents the electricity tariff based on the estimation of long-run marginal cost at generation, 33kV, and 415 voltage level for Ministry of Housing, Electricity...
Thermally coupled distillation sequences for ternary separations have been shown to provide significant energy savings with respect to the conventional direct and indirect distillation sequences. Although the Petlyuk column is generally more efficient than the other thermally coupled schemes, its structure creates potential operating problems because of the bi-directional vapour interconnecting streams...
In this paper, a new method for optimization of a wind–PV integrated hybrid system is presented. Based on deficiency of power supply probability (DPSP), relative excess power generated (REPG), unutilized energy probability (UEP), life cycle cost (LEC), levelized energy cost (LEC) and life cycle unit cost (LUC) of power generation with battery bank, the method addresses a specific location and employs...
Effects of UV stabilised polyethylene (UV+PE), IR absorbers polyethylene (IR+PE), double layers of polyethylene (D-Poly) and single layer of polyethylene (PE), as greenhouse covers, on aubergine growth, productivity and energy requirement were investigated in a late autumn season (2001). The late and final yields of plants grown in D-Poly houses were higher than those grown in UV+PE, IR+PE and PE...
Many energy-intensive process industries have complex material flows, which have a strong effect on the overall energy intensity of the final product (OEIF). This problem, however, has only been recognised qualitatively due to the lack of quantitative analysis methods. This paper presents an in-depth quantitative analysis of the effect of material flows on energy intensity in process industries. Based...
The recovery of condenser heat in air conditioners is attractive because of its great economy and environmental value. This work experimentally studies a modified air conditioner with a domestic hot water supply (ACDHWS) that operates in the space-cooling and water-heating mode. The working principles and the basic features of the ACDHWS are introduced in this paper. This is followed by an experimental...
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