摘要:

AbstractVapour jet compressors with multiple stages were studied and their performance characteristics with varying number of stages, waste heat temperatures and temperature boosts were obtained. The numerical model of the multiple‐stage vapour jet compressor is based on equations obtained by applying the theory of ejectors. Computer simulation proved to be an effective tool for obtaining performance characteristics of multiple‐stage vapour jet compressors. Results show that the COP does not necessarily increase with increasing number of ejector stages. Also, opting for a vapour jet heat pump with more than two stages will not contribute to improving its performance within the usual temperature ranges of industrial applicati

ISSN:0363-907X    

DOI:10.1002/er.4440170702

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractA comprehensive energy mapping of an oleochemical plant, for production of technical fatty acids and refined glycerol, was performed. Saturated water vapour is currently produced at 100°C from four flash vessels used to depressurize condensate streams emerging from different processing units in the plant. This vapour has a heat content of 314 kW and is currently condensed in a dump condenser and discharged. Incorporating an absorption heat transformer system would enable the recovery of almost half of this energy and a temperature lift of 34°C can be achieved. The heat transformer system delivers steam at 3 bar which can be fully reused in the plant.An economic analysis resulted in a pay‐off period of less than 18 months based on a steam cost of 14.25 $/GJ, an installed equipment cost of 535 $/kW, an annual operation time of 7200 h, and a heat transformer efficiency of 0.45. However, the pay‐off period depends on the estimated steam cost and heat transformer efficiency, and also on how much of the existing equipment can be utilized as components in the heat transformer. Installing the heat transformer would require minimum changes in the existing

ISSN:0363-907X    

DOI:10.1002/er.4440170703

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThe paper presents some recent results of the application of the detonation‐wave method for on‐line removal of ash deposit from the gas‐side surfaces of two coal‐fired steam boilers, each of 340 t/h nominal steam production. The older of the two boilers, although of similar design, had a classic refractory lining, and served as a sensitive test of the possible harmful effects of shock waves. The method was applied on two boilers as a daily cleaning routine instead of the originally installed soot blowers. Detailed observation over a period of 18 months showed a general improvement of boiler performances in comparison with previous practice. Careful monitoring of possible undesired side‐effects, such as the appearance of cracks or other damage on boiler structure and refractory walls, or excessive flue gas opacity, gave no cause for alarm and proved that the method is safe and in compliance with standard safety and environmental regulations. Some aspects of the design of the wave generators, their installation in boilers and operation are

ISSN:0363-907X    

DOI:10.1002/er.4440170704

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractIt is a well‐known fact that the temperature of the soil, some metres below the surface, is relatively stable. If this heat could be utilized by use of an earth tube heat exchanger, significant benefits could occur when space heating for buildings is considered. The inlet ventilation air is then led through a long earth tube in which it will, depending on their relative temperatures, take up heat from, or leave heat to, the surrounding soil. In this paper two case studies are presented. The buildings of concern are sited in the vicinity of Linköping, about 200 km south of Stockholm, Sweden. One of the cases utilizes heat from the earth tube in an air‐to‐water heat pump, while the other uses an air‐to‐air heat exchanger. The studies show that the earth tubes only to a very low degree contribute to the need of added heat in order to achieve a desirable indoor climate. Hence, the extra cost for the tube will not be balanced by the decreased cost for space heating. This discouraging result may have depended on heat pipes that were too short or the fact that the difference in temperature between the passing air stream and the surrounding soil was

ISSN:0363-907X    

DOI:10.1002/er.4440170705

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThis paper uses an aggregate modelling approach to assess the impacts of a redistribution of the taxes and duties that currently exist on crude oil and refined petroleum products in the Philippine economy. The approach used in the analysis consists of a general equilibrium model composed of fourteen producing sectors, fourteen consuming sectors, three household categories classified by income and a government. The effects of replacing the taxes and duties on crude oil and refined petroleum products with a more broad‐based tax on manufacturing and service sectors output on prices and quantities are examined. The results are revealing. For example, the consequences of redistributing the tax burden away from petroleum products to the manufacturing and service sectors of the Philippine economy would be an increase in output by all producing sectors of about 3.5% or about 2.4 hundred billion Philippine pesos, a rise in the consumption of goods and services by about 6.1% or 1.6 hundred billion Philippine pesos, a rise in total utility by 6.9% or 1.9 hundred billion Philippine pesos and virtually no change in tax revenue for the government. When subjected to a sensitivity analysis, the results are reasonably robust with regard to the assumption of the values of the substitution eleasticities. That is, while the model's equilibrium values do vary in response to different assumptions of the values of these elasticities, the fluctutations are not so enormous to suggest that the model is unrealistically sensititve to these parameter

ISSN:0363-907X    

DOI:10.1002/er.4440170706

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractDemand for energy in India is constantly on the rise and the conventional supply options available have failed to cope with this increase. The emergence of efficiency improvement, carrier substitution and renewable energy as alternative sources of energy supply, make adherence only to macro‐level energy planning unrealistic. A micro‐level (district/taluk) energy planning becomes pragmatic under these circumstances to pursue the goal of sustainable development and to harness locally available energy resources. This paper considers the energy consumption pattern in Bangalore North taluk in 1987–88 and projects the demand for energy in 1995–96. Taking into account the different energy sources used to provide different end‐use services through different end‐use devices, the paper presents a linear programming formulation for optimum allocation. The model considers the conventional and new alternative technologies for meeting the demand for energy service. The results show that substantial savings could be achieved by this optimal allocation. The cost savings could be to the tune of Rs 41.879 million in Bangalore North taluk during 1995–96 (terminal year of Eighth Five‐Year Plan). Energy savings of about 27% and cost savings of 16% could a

ISSN:0363-907X    

DOI:10.1002/er.4440170707

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractWater heating heat pumps are extremely energy efficient and large savings can be realized when they are compared to direct electrical resistance heaters. In spite of the energy efficiency of heat pumps, a large number of residential buildings in South Africa still use electrical heaters to heat water. The reason for this is that heat pumps are considerably more expensive than electrical heaters. Building owners tend to choose the system with the smallest initial cost and do not compare the two systems on the basis of life‐cycle cost. It is also difficult to calculate the life‐cycle cost of a heat pump because it depends on many factors like climatological conditions and water temperature. In this paper a methodology is developed to calculate the life‐cycle cost of a heat pump hot water installation. The model is used to investigate the effect of daily runtime, electricity tariff, hot water consumption and geographical location on the cost‐effectiveness of heat pumps. The cost‐effectiveness of heat pumps increases with daily run time, water consumption and electricity tariff. Heat pumps are more cost‐effective near the coast than in the interior. If sized correctly, heat pumps are more cost‐effective than electrical heaters for all major cities in South Africa. The cost‐effectiveness of heat pumps for two specific buildings, one a university student hostel in Potchefstroom and the other a hotel in Durban, is also investigated. For both cases it was found that heat pumps are more cost‐effective than direct electrical r

ISSN:0363-907X    

DOI:10.1002/er.4440170708

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractA low‐energy house located in Halifax, Canada, was monitored for a year using a computerized data acquisition system. Data on indoor and outdoor temperatures, relative humidities, and power consumption were collected for a whole year. The results of the analysis of cooling season data are presented. It was found that indoor temperature variations in the house were generally small, indicating a high level of comfort. The cooling load, and the cooling energy requirement of the house were low owing to the high level of insulation, and could further be reduced by increasing the thermostat setting. This however would reduce the comfort level in the house. Temperature set‐up during unoccupied periods did not reduce daily cooling energy requirement, and addition of an economizer control would not be feasible owing to the small magnitude of potential savi

ISSN:0363-907X    

DOI:10.1002/er.4440170709

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractGangues are waste residues from coal mining that have a low calorific value and a high ash content. They are full of difficulties when directly fired in fixed‐bed boilers (FBB). This paper presents the technology of gangue briquetting combustion in FBB and the prescriptions, briquetting conditions, basic properties, applied results, etc. of gangue briquetting fuels (GBF). Because GBF for use of FBB is widely available and relatively cheap, it is regarded as one of the fuels to be suitable for the national conditions of Chin

ISSN:0363-907X    

DOI:10.1002/er.4440170710

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

ISSN:0363-907X    

DOI:10.1002/er.4440170711

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY