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A prototype air cycle cooling system, designed for forced cooling of HPOF pipe-type cable, was built under an EPRI contract. Its main components are a turbine and compressor operated on a single high speed shaft and a compact cable. oil to air heat exchanger. Air cooling is supplemented by a spray water system. Tests were conducted on the prototype unit at the EPRI Waltz Mill Cable Test Facility to evaluate its performance and operating characteristics. This paper briefly describes this equipment and presents the results of the test program.

The monitoring of a waste separation process in the nuclear power industry is considered. Recent advances in gamma ray emission and electrical impedance tomography mean that it is now feasible to unite these two modalities into a novel dual-modality monitoring method. This paper considers a simple model problem for the identification of a boundary between two distinct waste streams in a semi-continuous rotation separator. The simplicity of the problem affords the opportunity to demonstrate the general feasibility of the approach whilst avoiding unnecessary complications.

Abstract Bioenergy crops are one of the renewable energy options available to decarbonise the energy sector in Scotland and help to achieve the overall planned target of 80% reduction in greenhouse gas (GHG) emissions by 2050. A process-based model for poplar and willow developed for simulating the effect of different environmental and management options on growth and biomass yield was used to estimate the GHG abatement potential (GHG-AP) under different crop management options in Scotland. The model results of annual wood yield did not show a strong relation with any of the environmental factors except that of initial soil organic carbon (SOC) content. Increasing plant density and decreasing harvest frequency increased GHG-AP. Application of N-fertilizers at a rate of 50–100 kg N ha−1 resulted in the buildup of carbon in soils with less than 180 Mg C ha−1. However, in soils with greater SOC contents, annual emissions resulting from N fertilizer application were greater than the carbon saving through marginal increases in wood yield and SOC changes. The best management scenario in terms of economic and environmental objectives depends on identifying an optimum plant density based on the site specific conditions with a fertilizer application of 20–100 kg ha−1 y−1 and a five year harvest interval. Even under the best economic scenarios, SRC willow and poplar have a GHG-AP ranging from 9.9 to 11.6 and 8.8–10.0 Mg CO2 eq. ha−1 y−1, respectively. Under the best environmental scenarios this range increases to 10.5- 13.2 and 9–11.1 Mg CO2 eq. ha−1 y−1 for willow and poplar, respectively.

Abstract Fouling is one of the most significant problems for internally enhanced tubes installed in the shell and tube condensers. Due to the lack of long-term test data, current fouling models are developed based on accelerated particulate fouling tests that have the low precision and hence are inapplicable for predicting combined fouling in most practical cooling tower systems. In addition, the constant values of fouling resistance (factor) recommended by the Air-Conditioning, Heating, and Refrigeration Institute (AHRI) are extremely limited under different operating conditions. To overcome these challenges, this research developed and validated two fouling prediction models based on experimental long-term tests. One of the models was in the form of a ratio of asymptotic fouling resistance of the enhanced tube to that of the plain tube ( R f ∗ / R f , p ∗ ), and the other one was in the form of the asymptotic fouling resistance of the directly enhanced tube ( R f ∗ ). Both models considered water quality, water velocity, and the tube geometries as the variables with the acceptable accuracy for prediction. 1) For the water quality, the parameter of valid concentration ( C com ) of cooling water was defined in this study, which reflected the potential amount of valid components to form the fouling. 2) For the water velocity, its impacts on the two critical parameters of the fouling process: sticking probability ( P ) and deposit bond strength ( ξ ) were investigated using experimental studies. Test results showed that in enhanced tubes with the increased water velocity the sticking probability ( P ) decreased continuously while the deposit bond strength (ξ) initially increased, and then, decreased. 3) For the tube geometries, by taking the parameters of tube geometries as variables the multi-variable correlations of the sticking probability ( P ) and deposit bond strength ( ξ ) were developed. From the results the generalized fouling prediction model as a ratio of asymptotic fouling resistance ( R f ∗ / R f , p ∗ ) was recommended for the application in HVAC&R industry due to its suitability and accuracy in practical project applications.

The natural hydrology of streams and rivers is being extensively modified by human activities. Water diversion, dam construction, and climate change have the potential to increase the frequency and intensity of low-flow events. Flow is a dominant force structuring stream aquatic insect communities, but the impacts of water diversion are poorly understood. Here we report results of an experimental stream flow diversion designed to test how aquatic insect communities respond to a low-flow disturbance. We diverted 40% to 80% of the water in three replicate streams for three summers, leading to summer flow exceedance probabilities of up to 99.9%. Shifts in habitat availability appeared to be a major driver of aquatic insect community responses. Responses also varied by habitat type: total insect density decreased in riffle habitats, but there was no change in pool habitats. Overall, the total biomass of aquatic insects decreased sharply with lowered flow. Collector-filterers, collector-gatherers, and scrapers were especially susceptible, while predatory insects were more resistant. Despite extremely low flow levels, there was no shift in aquatic insect family richness. The experimental water withdrawal did not increase water temperature or decrease water quality, and some wetted habitat was always maintained, which likely prevented more severe impacts on aquatic insect communities.

Abstract Renewable energy sources (RES) coupled to desalination offers a promising prospect for covering the fundamental needs of power and water in remote regions, where connection to the public electrical grid is either not cost effective or not feasible, and where the water scarcity is severe. Stand-alone systems for electricity supply in isolated locations are now proven technologies. Correct matching of stand-alone power supply desalination systems has been recognized as being crucial if the system is to provide a satisfactory supply of power and water at a reasonable cost. The paper covers plants installed since 1990 on the coupling of the two technologies. The main driver promoting the take up of this technology is that water is a limiting factor for many countries in the Mediterranean region. This paper presents the two technologies, RES desalination, and describes the most promising couplings such as PV–reverse osmosis, wind-mechanical-vapor compression, geothermal-multieffect distillation, etc as well as technologies selection guidelines. Also, included applications and lessons learned from specific applications as well as data on the economics. RES for desalination is an important challenge and useful work has been done. However in order to provide practical viable plants, much remains to be done.

Abstract Hydrogen sulphide is likely to become more common in produced hydrocarbon fluids, as the exploitation of deep reservoirs increases and unconventional resources get recovered significantly, such as heavy oils or bitumen. Hydrogen sulphide presence in produced oil and gas results in operational, environmental and treatment problems. Therefore, understanding the origin and the amount of hydrogen sulphide in petroleum reservoirs has great importance for petroleum engineers. Three natural processes are set forth to explain the generation of H 2 S in reservoirs: bacterial sulphate reduction, thermal cracking and thermochemical sulphate reduction (TSR). It is the TSR that leads to the largest amount of H 2 S. This phenomenon involves hydrocarbon oxidation and sulphate reduction and produces as by-products, hydrogen sulphide, carbon dioxide, carbonate minerals and heavy organo-sulphur compounds. The reaction mechanisms of TSR, as well as its kinetics, are not yet fully understood. In this paper, we checked the thermodynamic feasibility of TSR, at temperatures prevailing in the reservoirs where TSR is encountered. Firstly, we calculated the Gibbs energy of the reactions proposed by Worden and Smalley (Worden R.H. and Smalley P.C., 1996, H 2 S producing reactions in deep carbonate gas reservoirs: Khuff Formation, Abu Dhabi, Chem. Geol., 133, p. 157–171). We concluded that they are thermodynamically possible from 25 °C, confirming thermodynamic data published by Anisimov (Anisimov L., 1978, Conditions of abiogenic reduction of sulfates in oil and gas bearing basins, Geochem. Int., 15, p. 63) and Yue and co-workers (Yue C., Li S., Ding K., Zhong N., 2003, Study of thermodynamics and kinetics of CH4–CaSO 4 and H 2 S–Fe 2 O 3 systems, Chinese J. chem. Eng., 11, (6), p.696–700., Yue C., Li S., Ding K., Zhong N., 2006, Thermodynamics and kinetics of reaction between C1–C3 hydrocarbons and calcium sulfate in deep carbonate reservoirs, Geochem. J., 40, 87–94). Secondly, we used a non-stoichiometric approach without any pre-requisite chemical scheme this time. We calculated the Gibbs Energy of chemical systems composed by hydrocarbons, sulphur, anhydrite and water. The minimization of the Gibbs Energy lead to find the most probable chemical systems at steady state. Our theoretical results are consistent with the chemical schemes set forth for TSR by Orr (Orr W., 1977, Changes in Sulfur Content and Isotopic Ratios of Sulfur during Petroleum Maturation — study of Big Horn Basin Paleozoic Oils, in R. Campo and J. Goni Eds, Advances in onorganic geochemistry, Madrid Spain, Enadimsa, p. 571–595), by Worden and Smalley (Worden R.H. and Smalley P.C., 1996, H 2 S producing reactions in deep carbonate gas reservoirs: Khuff Formation, Abu Dhabi, Chem. Geol., 133, p. 157–171) and by Machel (Machel H.G., 2001, Bacterial and thermochemical sulfate reduction in diagenetic settings — old and new insights, Sedimentary Geology, 140, p. 143–175). Moreover, they are in concordance with some in-situ observations: anhydrite and hydrocarbon consumption with simultaneous formation of calcite, hydrogen sulphide and water. Our results showed as well that the larger the number of the carbon atoms in the reactant hydrocarbons, the more irreversible the reaction is.

SummaryStudies investigated the patient‐care (in‐hospital) and outside‐the‐hospital energy consumptions for delivering the hemodialysis (HD) service. A life cycle inventory methodology was used for this patient‐based analysis for two hospitals located in Wichita, Kansas. It was found that, for both hospitals, the actual HD machines consumed approximately 3.5 kilowatt‐hours (kWh) of electrical energy per HD, only 8% to 16% of the total energy used for delivering the HD service (in hospital). This increases to 9.6 to 28.9 kWh of hospital billable energy for the whole system of HD machine, auxiliaries, and dialysis water treatment. Converting these hospital direct electrical energy values to natural resource energy (nre) then adding the cradle‐to‐gate natural resource energy for the manufacturing and supply chain of all the HD consumables, the total is 78 to 149 kWh nre/HD. The nre measures all the direct fuel burned to generate energy and is thus directly related to emissions to the air, water, and land and is a direct secondary impact on public health from HD. The ratio of outside‐the‐hospital energy to direct hospital HD electrical energy consumption is 4:1 to 7:1, so a broader base exists for improvement than just the hospital.

Abstract A process based life cycle assessment of dimension stone production in the UK has been carried out according to PAS 2050. From a survey of eight production operations, on a cradle-to-site basis for UK destinations the carbon footprint of sandstone is 77 kgCO2e/tonne, that of granite is 107 kgCO2e/tonne and that of slate is 251 kgCO2e/tonne. These values are considerably higher for stone imported from abroad due to the impact of transport. Reducing the reliance on imported stone will contribute to emissions reduction targets as well as furthering the goals of sustainable development.