The Life and Legacy of William Rankine

Professor William Rankine, who was born on July 5 1820, made a substantial contribution to the science of heat and power and his influence in refrigeration and air-conditioning is still apparent today. This paper gives a short overview of Rankine’s life and work and then considers how his legacy is relevant to the challenges facing refrigeration, air conditioning and heat pump engineers in the 21st century. These include system efficiency, expansion methods, alternative cycles and novel working fluids

R-32 As An Alternative To Ammonia In Industrial Refrigeration

Ammonia is recognised to be the most commonly used refrigerant in industrial systems however it is limited in some applications by its toxicity. Â R-32 has similar flammability characteristics and a similar pressure-temperature relationship, and through its use as a blend component it has become widely used and readily available. Â This paper compares and contrasts ammonia and R-32 with specific reference to industrial applications. Â The analysis includes comparison of refrigerating effect, heat transfer performance and equipment size and looks at a variety of applications from low temperature freezers to high temperature heat pumps. Â Commercial factors such as price and availability are also considered. Â Opportunities for the adoption of new processes and materials, currently not feasible with ammonia are explored and the possible future trends in the industrial market are identified and evaluated. A hazard analysis for an industrial installation is described, showing the similarities to the type of analysis required for ammonia systems and identifying where the R-32 hazard analysis is different. The paper concludes with an assessment of the benefits that would be gained by the use of R-32 instead of ammonia, the constraints that would be required to make this happen and the likely probability of widespread adoption of R-32 in the industrial market

Key dating features for timber-framed dwellings in Surrey

This article is made available through the Brunel Open Access Publishing Fund. Copyright @ The Vernacular Architecture Group 2013. MORE OpenChoice articles are open access and distributed under the terms of the Creative Commons Attribution License 3.0.The main component of the Surrey Dendrochronology Project is the accurate dating of 177 ‘dwellings’, nearly all by tree-ring analysis. The dates are used to establish date ranges for 52 ‘key features’, which cover many aspects of timber-framing from building type to details of carpentry. It is shown that changes of method and fashion were in many cases surprisingly rapid, almost abrupt in historical terms. Previous dating criteria for timber-framed dwellings in the county have been refined and new criteria introduced. Clusters of change from the 1440s and the 1540s are shown and some possible historical links suggested.The Heritage Lottery Fund, the Domestic Buildings Research Group (Surrey), the Surrey Archaeological Society and the historical societies of Charlwood, Farnham and Nutfield

Calibration of key temperature-dependent ocean microbial processes in the cGENIE.muffin Earth system model

Temperature is a master parameter in the marine carbon cycle, exerting a critical control on the rate of biological transformation of a variety of solid and dissolved reactants and substrates. Although in the construction of numerical models of marine carbon cycling, temperature has been long-recognised as a key parameter in the production and export of organic matter at the ocean surface, it is much less commonly taken into account in the ocean interior. There, bacteria (primarily) transform sinking particulate organic matter into its dissolved constituents and thereby consume dissolved oxygen (and/or other electron acceptors such as sulphate) and release nutrients, which are then available for transport back to the surface. Here we present and calibrate a more complete temperature-dependent representation of marine carbon cycling in the cGENIE.muffin Earth system model, intended for both past and future climate applications. In this, we combine a temperature-dependent remineralisation scheme for sinking organic matter with a biological export production scheme that also includes a temperature-dependent limitation on nutrient uptake in surface waters (and hence phytoplankton growth). Via a parameter ensemble, we jointly calibrate the two parameterisations by statistically contrasting model projected fields of nutrients, oxygen, and the stable carbon isotopic signature (δ13C) of dissolved inorganic carbon in the ocean, with modern observations. We find that for the present-day, the temperature-dependent version shows as-good-as or better fit to data than the existing tuned non-temperature dependent version of the cGENIE.muffin. The main impact of adding temperature-dependent remineralisation is in driving higher rates of remineralisation in warmer waters and hence a more rapid return of nutrients to the surface there – stimulating organic matter production. As a result, more organic matter is exported below 80 m in mid and low latitude warmer waters as compared to the standard model. Conversely, at higher latitudes, colder water temperature reduces the rate of nutrient supply to the surface as a result of slower in-situ rates of remineralisation. We also assess the implications of including a more complete set of temperature-dependent parameterisations by analysing a series of historical transient experiments. We find that between the pre-industrial and the present day, in response to a simulated air temperature increase of 0.9 °C and ocean warming of 0.12 °C (0.6 °C in surface waters and 0.02 °C in deep waters), a reduction in POC export at 80 m of just 0.3 % occurs. In contrast, with no assumed temperature-dependent biological processes, global POC export at 80 m falls by 2.9 % between the pre-industrial and present day as a consequence of ocean stratification and reduced nutrient supply to the surface. This suggests that increased nutrient recycling in warmer conditions offsets some of the stratification-induced surface nutrient limitation in a warmer world, and that less carbon (and nutrients) then reaches the inner and deep ocean. This extension to the cGENIE.muffin Earth system model provides it with additional capabilities in addressing marine carbon cycling in warmer past and future worlds

Practical strategies to stabilize a nanosatellite platform with a space camera and integrated mechanical parts

The growth and speed of nanosatellite capabilities has led to an increasing demand on the respective attitude control systems. Typically, nanosatellites utilise minaturised reaction wheels for 3-axis stabilisation/manoeuvres, which are desaturated using magnetorquers. Small space telescopes have been deployed from nanosatellites in the past with capability ever increasing to push the limit of detectors. Previous work has established the feasibility of achieving GSD of 0.7 m in low Earth orbit for a 2.5 U CubeSat using deployable mirrors from a 400 km orbit. The dynamic model of nanosatellite with the telescope + the deployed mirror systems will be built in this research work. The deployed mirror system will use a diamond turned mirror - it's an off axis paraboloid. The mirror would be light-weighted as much as possible, i.e. the back surface would be carved away with good thermal stability. The mechanisms for mirror systems may use methods like minature geared motors, stiction motors and shape memory alloy hinges. The sensoring and directing of the mirror surface will use an image based detection methods. A closed loop control of the mirror position will be used to iterate to a fully aligned system. This work also considers control strategies to stabilise such a platform against the effects of firstly, the external aerodynamics and secondly, any internal disturbances induced by and the movement of focussing elements. A pointing accuracy of 5-10 arcsec for a 20 min observation over the UK is targeted at a baseline orbit of 350 km sun-synchronous. Following an initial baseline to establish current state-of-art both based on in-orbit performance and off-the-shelf subsystems available to the market within the constraints of a 3U nanosatellite system, a number of feed-forward/feedback control loops and sensor systems are studied to determine a simple process for compensating for the motion