The use of waste heat in a solar still

There are instances in remote areas where heat is being wasted, e.g., in internal combustion, engines, etc. Some of this heat can be recovered to produce distilled water in solar stills.

The solar still replaces the cooling tower, ponds, or radiators normally used to control the engine temperature. The diesel cooling water in such a system remains separate from the saline water in the solar still.

The advantages of using such a system compared with a conventional solar still are:

1. (a) water costs are very much reduced

2. (b) the area occupied is much less, i.e., about 1/5th

3. (c) production has much less seasonal variation

4. (d) the efficiency of the solar still is improved due to the higher operating temperatures.

From experiments conducted at Highett using a Mk VI solar still fitted with a simple heat exchanger and a separate electrically-heated source of hot water to simulate the waste heat, design data are not available for application to working systems. The information required to match a solar still to a diesel's cooling requirement is:

1. (a) engine efficiency

2. (b) hourly fuel consumption

3. (c) hourly solar radiation

4. (d) hourly ambient temperatures.

A by-product of this work has been the production of a “solar water heater” which costs less than that of the cheapest conventional system. This “solar” hot water system uses a heat exchanger similar to what is used to transfer the waste heat to the saline water. It is envisaged to have hot water productions approximately the same as the distilled water productions. The influence of hot water production on the output of the waste heat solar still is discussed.     

On enthalpy management in small buildings

Enthalpy management requirements of residential and small commercial buildings are analyzed and integrated approaches to energy-efficient and cost-effective heating and cooling schemes are proposed. Improved design and operating strategies are suggested to make more efficient use of off-the-self (or other readily accessible) technology for space conditioning. The use of Comfort Range Thermal Storage (temperatures in the approximate range of 65–75 °F) and special operational strategies are central to these approaches. Fossil-fuel heaters, heat pumps, solar collectors, electric driven air coolers, all can be used more efficiently when they are effectively interfaced with selected thermal storage systems. A central heated (fossil fuel) and cooled (electric air-conditioner) residence located in Long Island, New York, is considered as an example. With Comfort Range Thermal Storage, it is found that the revised operating approach leads to 50% savings in space conditioning costs, with the basic functional features of the building unchanged from those of a typical well-insulated frame residence. Additional insulation results in further savings.

Devices, methods and strategies employed to achieve these results include the use of Comfort Range Thermal Storage as well as one or more of the following:

1. (1) Variable firing rate fossil fuel heater.

2. (2) Thermally purgeable fossil fuel heater.

3. (3) Outside air for all fossil fuel heater requirements.

4. (4) Separation of the combustion and heat transfer function from the thermal storage function of a conventional boiler.

5. (5) Use of off-peak electrical energy.

6. (6) User-oriented controls for space conditioning applications to allow conscious reprogramming of temperature to suit variations in life-style of the occupants.

7. (7) Control of energy flow at windows during the heating and cooling seasons.

8. (8) Comfort Range Thermal Storage in the temperature range of 65–75 °F.

9. (9) Functionally composite building materials.

Not all the above options are suitable for inclusion in new structures. Not all can be retrofitted to existing structures. Nevertheless, substantial energy and cost savings are selectively possible in all cases of fossil-fuel heating systems. Retrofitting of existing masonry buildings promises particularly significant economies. Such structures are typically uninsulated. Retrofit strategies which include insulation, permit economies substantially greater than those which result solely from the insulation-prescribed reduced heat losses. Such retrofitting, as well as the retrofitting of substantial thermal storage capacity to existing insulated frame buildings can result in substantial cost reductions for space heating and cooling.     

Regional economic growth and the need for power in New England

New England faces a serious shortage of electricity generating power within 5 years, and unless capacity is built in the 1990s the region may suffer large economic losses. Reserve margins may fall below 20% by 1990, and no later than 1992. By the mid-1990s the region could experience a shortfall of 3000–7000 MW. The costs of this shortfall are conservatively estimated to be:

• • $20–50 billion (billion—10⁹) in lost economic product (1986 dollars),

• • $3–8 billion in lost business profits,

• • 400 000–900 000 jobs lost,

• • $3–7 billion in state and local government tax revenues lost,

• • 2% reduction in regional GNP by the year 2000.

Feasible options available to prevent this are imports from Canada and construction of new plant. Conservation can make only a small reduction in slowing electric growth, cogeneration can only prevent the shortfall from getting larger, and various renewable alternatives (solar, wind, wood, waste, etc.) cannot make significant contributions. While opportunities exist in contracting for Canadian hydro-power purchases, there are high economic risks in relying solely on it. Thus, New England utilities and regulators should consider adding new electric capacity.     

French developments in the ultrasonic examination of pressure vessels

In 1985, 34 Pressurized Water Reactors (PWRs) were already in service in France and 21 were being constructed. The manufacturer (Framatome) and the owner (Electricité de France, EDF) have consequently gained great experience in the ultrasonic examination of the various components and particularly of the reactor vessel.

The development work initiated concerns:

• —the improvement of the knowledge of methods used;

• —the beginning of automation in fabrication control;

• —the continuation of the technical implementation of the signal and image processing.

At the fabrication stage, work was carried out to demonstrate the total adequacy of those examinations required by the RCCM Code.

In addition, Framatome is developing the automation of ultrasonic inspection in shop.

Inservice inspection of the vessel is carried out with ‘MIS’ inspection equipment.

Data analysis is improved by special software allowing the performance of different types of UT indications to be presented.

Diffraction echoes from focused probes are used to size underclad defects on reactor nozzles.     

A comparative analysis of three of ERDA''s major R & D programs

The benefits attributable to alternative energy R & D programs should be evaluated in terms of how well the technologies contribute as integral elements of the total United States energy system (rather than as isolated entities, as has typically been done in the past). Thus, the present model simulates the dynamics of the evolution of the total energy system by requiring both existing and new technologies to compete for introduction (i.e. commercialization) on a cost-competitive basis that considers the time phasing of

1. (1) retirement of energy conversion facilities,

2. (2) growth in end-use demands, and

3. (3) escalation of the costs of extracting depleting domestic energy resources.

This approach contrasts with a static model used by the Energy Research and Development Administration (ERDA), wherein assumptions must be made for each future year of interest for

1. (1) maximum capacity constraints for alternative types of conversion facilities and

2. (2) the cost of energy resources.

The present model is used to compare the relative consequences and merits of the technology products from the following three of ERDA's major energy R & D programs:

1. (1) the liquid-metal fast breeder reactor (LMFBR),

2. (2) synthetic fuels derived from coal and oil shale, and

3. (3) improved efficiencies for end-use devices (e.g. space heaters).

It is found that the development of synthetic fuels derived from coal and oil shale is the only alternative (of the three considered) that provides energy independence for the United States in the next fifty years. However, the possible collapse of the world oil cartel is shown to pose a major retardant to synfuels commercialization by the private sector until at least the end of the century. The substantial environmental impact from synfuels commercialization could be reduced significantly with the accelerated introduction of end-use utilizing devices with improved efficiencies. This latter program could result in a significant reduction in the costs of operating the United States energy ststem over the 60-yr period considered by the model. The discounted present value of this “cost reduction” (i.e. the “economic benefit”) would be two orders of magnitude greater than the R & D investment, at least one order of magnitude greater than the expected economic benefits from synfuels commercialization and two orders of magnitude greater than the economic benefits from the commercialization of the LMFBR. However, the lack of performance and cost studies of improved efficiency in end-use suggests increased funding for these technologies rather than reduced funding for the breeder.     

Studies on membrane viscosity stabilized solar pond

In this nonsalt type of solar pond, the nonconvecting layer is composed of a viscous polymer solution partitioned by a number of transparent films. An advantage of partitioning is that a thinner polymer solution can be used and that the light transmittance increases. Results of experimental and theoretical investigations on the performance of this solar pond are summarized as follows:

1. 1. Ionized polyacrylamide solution was chosen as the thickener based on tests about solubility, viscosity, light transmittance and stability.

2. 2. The critical temperature difference for the onset of convection in the polymer layer (ΔT/L)_cr [°C/m] was given by the following formula based on the measurements in various thicknesses of the polymer layers (L) [m] and various concentrations (ζ) [%],

(ΔT/l)_cr=(55−185lnL)exp(4.66L^0.505lnζ

3. 3. An outdoor model pond, 200 × 150 cm surface and 100 cm depth, was constructed in Osaka. Four types of model ponds were tested, and the availability of membrane type with partition films was confirmed.

4. 4. The theoretical temperature rise of the pond using a one-dimensional model was calculated by solving the equations of the heat balance in the pond. As a result, the optimum values of thickness of polymer layer and number of films was determined

     

A decision analysis of the U.S. breeder reactor program

Past modelling efforts have failed to reach a consensus on breeder R & D strategy. These failures have led some to question the usefulness of benefit-cost analysis for a problem as complex and as politicized as this one has become. Our paper examines some of the major weaknesses of past benefit-cost analyses and then reformulates the breeder investment decision in a decision tree framework. Decision analysis is used to evaluate alternative R & D strategies that range from accelerating the current effort to abandoning the entire program.

Breeder benefits are assessed through ETA-MACRO, a model of interactions between the energy sector and the rest of the U.S. economy. A dynamic non-linear optimization procedure is used to examine how breeder timing could depend upon alternative assumptions with respect to:

1. (a) uranium supply,

2. (b) energy demand growth,

3. (c) environmental constraints upon coal and shale oil production, and

4. (d) the availability of alternative energy sources.

Subjective probabilities have been estimated through a Delphi questionnaire on the critical uncertainties. Each individual's responses have been used independently to calculate an optimal strategy. A fairly simple rule-of-thumb has emerged from this experiment. If a respondent believes that the probability of positive benefits (P) exceeds 0.03, there are positive expected dollar benefits from any breeder development program. If P is less than 0.03, however, the expected economic benefits of such a program would be negative. The costs of the R & D program would then exceed their actuarial value.     

How competition might affect electric-utility DSM programs

This paper discusses competition in the electricity industry and how it might affect utility DSM programs. The roles that state regulatory commissions could play to affect retail competition and DSM programs are examined. Commissions could set exit or reentry fees for customers who want to buy electricity from an entity other than the local utility. Or they could ‘tax’ the use of the local distribution system to discourage uneconomic wheeling and to pay for DSM programs. The effects of DSM programs on retail electricity prices and how utilities might redesign their DSM programs for a more competitive environment are considered. In the future, utility DSM programs may

1. (1) focus more on customer service and less on system-resource benefits,

2. (2) emphasize capacity reductions more and energy savings less as utilities seek to minimize the lost revenues associated with DSM,

3. (3) become more cost-effective as utilities identify better ways to deliver DSM services at lower cost, and

4. (4) involve fewer inter- and intraclass transfers as utilities increasingly have individual customers pay for their own DSM services. While DSM programs in the future may be different from what they are today, they will continue to be important to utilities as powerful marketing tools and to society because of their environmental and economic-productivity benefits.

     

Leak-before-break in French nuclear power plants

Practical applications of the leak-before-break concept at the present stage are quite limited in French nuclear power plants. However, discussions with safety authorities have included leak-before-break arguments for the different types of reactors: pressurized water reactors (PWRs), liquid metal fast-breeder reactors (LMFBRs) and gas graphite reactors (GGRs).

At present, the fracture mechanics part of the studies are complete for the following components:

• —pipes in GGRs;

• —primary and auxiliary lines in PWRs;

• —steam-generator tubes in PWRs;

• —pipes and main vessels in LMFBRs.

The different approaches are consistent but some specific problems have to be taken into account, depending on the plant, such as creep regime, thin shell components, in-service inspection or the issue of design safety.

A large research and development program, realized in different cooperative agreements (national or international), completes the general approaches. It comprises different topics, such as material properties, elastoplastic fracture mechanics, leak-area determination and leak-detection devices.

Although practical applications are limited at present, EDF, in conjunction with Framatome, Novatome and CEA, will define a complete validated methodology to be used on a variety of cases.     

Calibration results on a new integrating instrument for measuring daily values of total solar radiation

Test results are reported for a newly develope instrument for accurately measuring daily solar radiation. The instrument consists of two components: the radiation sensor (a silicon-cell pyranometer that is mounted outdoors in the same way as the conventional Eppley or Kipp pyranometer), and the integrator (a conventional household style d-c ampere-hour meter). No electric power is needed to operate the instrument, which is easily portable, reasonably robust, and inexpensive.

Calibrations were done in Barbados (latitude 13° 12′ N) over an eight-month period, and consisted of intercomparison of a number of the new instruments among themselves, as well as calibration against conventional Kipp and conventional Eppley solar radiation measuring systems.

Test results led to the following conclusions:

1. 1-Scatter in the daily values of solar radiation as measured by the new instruments, due to the inherent characteristics of the new instruments themselves, was within ±2 percent.

2. 2-When compared to a carefully maintained reference (Kipp or Eppley) system, the scatter of the calibration data was within ±3 percent.

3. 3-Because of the difficulty of accurately integrating the solar-radiation record that is obtained with conventional (Kipp or Eppley) systems in the coastal tropics (where cumulus cloud is prevalent), scatter of the calibration data over many months was as high as ±10 percent, but more than half of this scatter was attributable to the reference system and not to the new instruments.

4. 4-Although developed mainly for use in the tropics, the new instrument is suitable for year-round use at latitudes up to 35 or 40 degrees, and for summer use at even greater latitudes.

5. 5-Being portable and inexpensive, and at the same time surprisingly accurate and robust, the new instrument seems well suited for measuring solar radiation in such situations as irrigation control, estimating evaporation from dams, horticultural and agricultural research, and for meteorological and climatological purposes.

     

The second ASTM/ESIS Symposium on Constraint Effects in Fracture; an overview

The Second ASTM/ESIS Symposium on Constraint Effects in Fracture attracted a total of 24 contributions. These papers addressed various models to characterize, quantify and predict constraint effects, as well as experimental/validation studies and application studies. Available constraint models include the mechanics-based approaches of two-parameter fracture mechanics (2PFM) (i.e. J-T, J-Q, J-A₂, J-_g), statistical techniques based on the Weibull model, and micro-mechanical approaches applicable to fracture by both cleavage and ductile mechanisms. Collectively, these strategies extend significantly the range of loading conditions to which a fracture mechanics methodology can be applied to assess the integrity of an operating structure. At this stage, the following general statements can be made:

1. (1) In the lower transition regime where cleavage fracture occurs before or just shortly after the onset of ductile tearing, all of the 2PEM constraint models can be applied to parameterize the variation of critical fracture toughness with constraint. Of the various models available, the J-Q approach of O'Dowd and Shih applies rigorously to the highest deformation levels and to the broadest range of materials. Experimental evidence is available which shows the validity of this approach. All of the 2PEM approaches, however, suffer from the disadvantage that they complicate considerably the task of characterizing material toughness because toughness becomes a function of constraint at every temperature rather than a single value.

2. (2) In the lower transition regime it is also possible to predict without resort to empirical argument this variation of toughness with constraint using the results of standard fracture toughness tests coupled with the micromechanics approach of Dodds and Anderson. At the second Symposium, the applicability of this model was extended into the upper transition regime where significant stable tearing may precede the onset of cleavage. Again, experimental evidence is available which shows the validity of this approach. Certain issues remain with respect to the proper treatment of 3-D effects; these are currently under investigation.

3. (3) A “master curve” approach to the analysis of fracture toughness data in the transition regime has been proposed in a draft ASTM standard on this topic. Combination of this approach with a statistical correction for thickness effects based on the Weibull model appears to provide a powerful tool for the predicting toughness of geometrically similar specimens from one another (e.g. thick C(T)s predicted from thin C(T)s) across a wide range of thicknesses.

4. (4) 2PFM models can be applied on the upper shelf to parameterize constraint effects on R-curve behavior. However, in this application the theoretical basis of these approaches is lost as a reference infinite body field solution that is self-similar to the field solution for growing cracks in finite bodies is not available. As a consequence, it can be expected that “size effects” would likely reveal themselves in such an application. On the upper shelf the way forward appears to be through application of some form of local approach wherein sub-continuum material variables are incorporated into the models to provide a capability to predict accurately structural behavior from test results.

     

Energy cost of living, 1972–1973

The total energy requirements of household consumption of all goods and services have been calculated. Source for consumption data is the 1972–1973 Bureau of Labor Statistics (BLS) Consumer Survey. These are converted to energy terms using input-output energy intensities. The dependence of household energy use on expenditures, number of household members, degree of urbanization, and other demographic-economic factors, has been investigated graphically and statistically. The major factor determining energy requirement is expenditure level, but this can be affected by up to about 15% by variation in the other factors. In agreement with previous work based on the 1960–1961 BLS Survey, we find that

1. (1) the dependence of total energy requirements on expenditures shows a tendency to saturation;

2. (2) about one-half of the total energy of the average household is a result of the purchase of fuels and electricity while the other half results from the purchase of non-energy commodities.

Application to the analysis of an energy tax and rebate program is discussed briefly.     

Issues in biomass technologies for synthetic fuels from coal and biomass resources in the Midwestern U.S.A.

Discussions on the role of biomass in the development of a midwest synfuels industry brought general agreement on:

1. (1) the continued development of new techniques for ethanol production;

2. (2) use of corn as a feedstock for ethanol;

3. (3) large-scale plants are more economical than farm-scale ethanol plants; and

4. (4) tax subsidies to promote use of ethanol.

     

A simplification of weather data to evaluate daily and monthly energy needs of residential buildings

Hourly, daily, monthly and annual heating and cooling requirements of a residential building located in Ottawa, Ontario, Canada were estimated, employing ENERPASS as the energy simulation tool, and performing hour-by-hour energy analysis. The following weather data were employed:

1. (i) Ten years (1967–1976) of weather data. The ten-year average of the results is identified as TYA.

2. (ii) A typical meteorological year (TMY) generated using the same ten years of data.

3. (iii) Two different hourly ambient air temperature distributions (T1 and T2) for a typical day in each month. The solar radiation on each surface was estimated using the mean monthly clearness index.

The house use patterns, including heat generation and the thermostat setting, were taken the same when using TYA, TMY, T1 or T2. The analysis was carried out for the house as it is (well insulated and airtight), and for two modifications: one with larger infiltration rate and lower wall thermal resistance, and the other with larger south-facing window area and using super-windows. The results of this study show that the long-range hourly, daily, monthly and annual heating and cooling requirements of a residential building located in a cold climate can be predicted by employing mean daily maximum and minimum temperatures and the mean monthly clearness index for each month. This amounts to substantial savings in computational costs, in either using many years of weather data or generating a TMY for the site. For locations lacking detailed hourly weather data, the use of data and the procedure outlined in this study may be employed to predict the long-range thermal performance of simple residential buildings.     

Issues in coal technologies for synthetic fuels development in the Midwestern U.S.A.

A two day meeting involving researchers, industrialists, and state policymakers on the subject of coal technologies and synfuels brought general agreement on:

1. (1) the lack of a cohesive energy policy regarding coal in the United States;

2. (2) the need for long-term constancy in the regulatory environment;

3. (3) the need for coal research and development; and

4. (4) the use of conflict resolution techniques to solve synfuel issues.

     

Findings of the second international conference on energy use management—ICEUM-II

It is evident that future worldwide patterns of energy use will be modifications of current ones. The objective of this work is to understand the directions these modifications are taking and to assess opportunities for bringing about beneficial changes and avoiding detrimental ones.

The future will see greater deficits of conventional fuels such as oil and gas and the certainty of higher prices. Fuel and electricity prices, already at record highs, are seen to double again in the next 1–2 years. As a consequence of potential scarcity, disruption of supplies and economic pressures, the danger of a major war is greater now than it has been in the past several decades. The problem is compounded by the fact that the public, in general, is not convinced there is a serious problem and is not prepared to take decisive action.

The United States—the world's major energy user—plays a pivotal role. The consequences of an ineffective U.S. national energy policy have been that U.S. imports remain high, oil prices stay high, the world economy is less stable and less oil is available for other nations. Commensurately, increased prices for food, industrial products, and transportation are resulting.

At this time, changing energy futures is less a problem of technology and more a problem of motivation, values and social awareness. New technology is available for many industrial processes, for heating and cooling buildings, for lighting and agriculture. New technology is urgently needed for energy efficient transportation. Unresolved are the issues of how best to educate and inform the public and to instill new values appropriate for the future. The public, in general, still is not convinced that there is a serious problem and still is not prepared to take decisive actions.

New energy resources are widely sought as replacements for conventional ones, especially those which are imported. While these efforts will lead to varying degrees of success, energy use management has been established during the decade of the 1970s as an effective near-term ‘resource’. It is the most immediate, least risky, cheapest and least environmentally damaging of all the potential options for solving energy problems. National and international policies must be modified to vastly increase the priority given this resource.     

Different strategies for operation of flat-plate solar collectors

Three strategies for solar collector operation are defined. These involve keeping one of the following constant during the day:

1. (i) the average working fluid temperature,

2. (ii) the outlet temperature and

3. (iii) the inlet temperature.

A graphical and analytical method previously developed by the authors was generalized to analyse and compare these strategies. For a constant flow rate, the best strategy is to maintain a constant inlet temperature. A constant outlet temperature is recommended when flow-rate control is possible.     

Diseases and pests in energy crop plantations

The Pest and Disease Management Activity was established in response to an awareness of the potential importance of pests and diseases in woody biomass production systems. Annual surveys in Canada, Eire, England, N. Ireland, Scotland and Sweden from 1987–1991 confirmed that rust disease (Melampsora spp.) is currently the most serious problem in willow biomass production in Europe. Other pests and diseases cause problems only on a local scale, though they could become more generally severe. Increasing clonal susceptibility to rust and an an increasing association of premature defoliation with lower rust severity levels have occurred over the period. A high degree of intrinsic variability in pathogen populations is expressed as four formae speciales (f.spp.) and at least eight pathotypes of the most common rust species, M. epitea. The same f.spp. appear to occur among pathotypes in Sweden, New Zealand and the UK. A network of field experiments has been established, in collaboration with the Joint Trials Activity, to enable the rust pathotype composition to be compared between five countries. It also aims to identify an international set of standard willow clones to be utilized for characterizing rust pathotypes globally.     

Energy and environmental policies of the developed and developing countries within the evolving Oceania and South-East Asia trading bloc

The considered countries are categorised on the bases of their levels of economic development and indigenous energy resources, e.g. being either

• • advanced industrialised, and either energy rich (e.g. Australia) or energy poor (e.g. Singapore); or

• • developing, and either energy rich (e.g. Indonesia) or energy poor (e.g. the Philippines).

For each country, its energy balance (including considerations of resources, rate of consumption, fuels-demand split as well as the degree of national self-sufficiency with respect to each fuel) is related to the rate of economic development of the nation state.

This paper explores the growing interdependency between developed and developing countries that are (i) within an evolving trading bloc and (ii) are energy rich or energy poor.     

A cellwise method for the optimization of large central receiver systems

The total number of heliostats in the collecter field determines the approach to the optical simulation problem. For large central receiver systems, it is desirable to introduce a cell model which establishes an array of representative heliostats (see Ref.[1] for central receiver systems). We now have an arsenal of computer programs which allows us to optimize the arrangement of heliostats in the collector field subject to the approximations of the cell model. Each cell contains an arbitrary regular two dimensional array of heliostats. For practical reasons we have limited our current study of the 100 MWe commercial model to four categories of heliostats arrangement; (1) radial cornfields, (2) radial staggers, (3) N.-S. cornfields, and (4) N.-S. staggers.

The most important results from the 100 MWe commercial model optimization study are:

1. (1) Staggers are better than cornfields.

2. (2) The increased cost of the tower and receiver subsystems has moved the solution to a larger cell size and a shorter tower.

3. (3) No panels should be deleted from the south side of the cykindrical receiver, and

4. (4) The collector field trims to a 360° configuration.

The center of the collector field is north of the tower and some compromise may be made to prevent excessive panel power asymmetry. Currently, this problem is solved by using preheat panels in the southern part of the receiver.