4 research outputs found
Waste heat recovery using fluid bottoming cycles for heavy duty diesel engines
Full text linkA typical long-haul heavy duty Diesel engine currently rejects up to 50% of the total fuel energy in the form of heat. Due to increasing CO2 emissions and fuel costs, there is a growing interest in techniques that can even partially utilise this wasted resource to improve the overall system efficiency. Fluid Bottoming Cycles (FBC) including Rankine and organic Rankine cycles offer one means towards converting waste heat into usable power. This thesis investigates the potential of FBCs to improve the net power of two computationally modelled (Ricardo WAVE V8.1) 10 litre engine platforms operating at Euro 6 emission levels. The heat to power conversion potential of a FBC largely depends on the selected working fluid, its associated cycle operating mode and the system architecture. Firstly, a detailed systematic methodology for the selection and evaluation of pure working fluids was developed and applied using an advanced chemical process modelling tool (Aspen HYSYS V7.3). Using cycle and fluid fundamentals, screening criteria, and ranking indices, the methodology identified ethyl iodide, methanol, R30, acetone, R152 and E152a as the most suitable fluids amongst the 1800 synthetic, organic and inorganic fluids. Secondly, by varying the expansion inlet parameters, simulations were conducted using 10 pure, dry, isentropic and wet working fluids. The aim was to reduce cycle irreversibilities, highlight the significant sensitivity and performance results, provide directions for practical implementation, and offer new opportunities in energy conversion. For the low, medium and high thermal boundary conditions respectively, liquid expansion (E152a), low pressure limited superheat expansion (methanol, R30, acetone) or dry supercritical expansion (R152), and high pressure limited superheat expansion (using the high temperature organic fluids) were identified as techno-economic optimum. These optimal ORC operating modes achieved efficiencies 65-77% of the theoretical cycle limits. Finally, 13 combinations of thermal and sub-system architectures were methodically analysed and classified in terms of their level of complexity, average system power and relative size. To provide tailored solutions, the pure working fluid methodology was additionally adapted to examine over 750 water blends and 700 organic blends. Aqueous blends of 3-Methyl-1-Butanol and 1-propanol were found to be best suited to the dual pressure and the dual cycle systems. Furthermore, the ethanol-toluene blend was preferred for the high temperature recuperated cycle. The dual cycle system (aqueous blend and E152a combination) showed the maximum potential and produced an average of 7.5% of additional engine crankshaft power
A study of organic Rankine cycle systems with the expansion process performed by twin screw machines
No full textThe prediction of the performance of energy systems that recover power from low grade heat is one of the most important requirements for reducing their investment cost and optimising system efficiency. The aim of this work was to study, model and analyse an Organic Rankine cycle (ORC) system using a twin screw expander to generate the power output, with HFC-245fa, as the working fluid. A software package (Power Plant Performance Prediction Program), simulating ORC system performance was therefore prepared for this purpose. Major components were represented by proper units and relations between the system’s constituents defined. The preferred analytical procedure depends on both the system complexity and the requirements of the study. In this case, the whole cycle was simulated in order to obtain a good understanding of its behaviour with the aim of estimating its optimum operating conditions. The procedure adopted was to start from a basic case and then improve it, in a realistic way, in order to evaluate the system potential. Performance indicators, like thermal efficiency, specific net output, total UA and surface of the heat exchangers, as well as the relative cost of the system all need to be taken into account but it is impossible to optimise all of them simultaneously. The design value for these parameters is therefore a matter of choice, or compromise.
Efficiencies of ORC systems were calculated based on the assumption that the working fluid entered the expander as wet vapour. For the heat source and sink conditions chosen for this study, the overall cycle efficiency was estimated as approximately 6% using R245fa. This and the power output are highly dependent on the ambient air temperature when using air-cooled condensers. Allowing for a small degree of subcooling at the condenser exit, it is shown that the heat recovery should be maximised
Stepping out of the Vehicle: The Potential of Arizona v. Gant to End Automatic Searches Incident to Arrest beyond the Vehicular Context
Full text link“Because the law says we can do it” was the response Officer Griffith offered when asked why officers searched Rodney Gant’s car when he was arrested for driving with a suspended license. Officer Griffith’s honest answer exemplifies the effect of prior Supreme Court decisions on search incident to arrest power in the vehicle context: that a vehicle search incident to arrest is a police entitlement divorced from any rationale whatsoever. Concerns for officer safety and preservation of evidence -- legal justifications that generally permit warrantless searches incident to arrest generally -- had been utterly abandoned by the Court in the automobile context. This police entitlement led to invasions of privacy against persons guilty of no more than mere traffic violations, as searches were conducted simply because they were legally permissible. However, the Supreme Court in Arizona v. Gant shifted course and strengthened Fourth Amendment protections by terminating the entitlement that permitted vehicle searches incident to arrest as a matter of right.
The tumultuous jurisprudence of the search incident to arrest doctrine under the Fourth Amendment has often produced inconsistent and varied results. In keeping with this tradition, the Supreme Court in Gant revised nearly thirty years of search incident to arrest law in the automobile context. Unlike Gant’s predecessors, Gant generally enhanced Fourth Amendment protections against unreasonable searches by holding that automatic vehicle searches incident to arrest are unconstitutional. On the other hand, Gant’s second holding created a new warrant exception to govern searches of automobiles incident to arrest by allowing officers to search a vehicle, even when the justifications of officer safety and preservation of evidence are nonexistent.
The author argues that Gant not only enhances Fourth Amendment protections overall by limiting authority to search an automobile upon arrest, but that its first holding also undermines other cases permitting automatic searches incident to arrest in non-vehicular situations. Gant’s affirmation of two specific rationales that permit a search incident to arrest, officer safety and the preservation of evidence, directly conflicts with non-vehicular cases that allow automatic searches irrespective of these rationales. Since Gant undermines such cases by reconnecting the search incident to arrest exception with its justifications, applying Gant to cases that permit automatic searches of containers on the person, and certain automatic home searches incident to arrest, serves to enhance privacy protections against these non-vehicular searches that have become police entitlements.
Part I outlines the judicial origin of search incident to arrest law and its schizophrenic history, exposes the fundamental conflict between the cases, and discuss the legal rules and reasoning of Gant. Part II argues that the standard governing Gant’s second holding is vague, and is concerned with whether the crime of arrest involves tangible evidence rather than a quantum of proof analysis prevalent in standards such as probable cause and reasonable suspicion. Part III analyzes the effect of applying Gant’s first holding to an automatic search of containers on the person incident to arrest, while Part IV applies Gant to certain automatic home searches incident to arrest. Part IV also addresses some Counterarguments and potential pitfalls. This Comment concludes that Gant’s retraction of the search incident to arrest power may serve to end, or at the least severely undermine, automatic searches of containers on the person and homes incident to arrest
Impact of a pandemic on the sporting world: Analyzing potential contractual disputes in sports due to the spread of COVID-19
No full textBeyond its extremely concerning health-related implications, COVID-19 has also massively impacted trade and business across all sectors. The realm of sports specifically has faced major setbacks, as most sporting leagues and events have been postponed, cancelled, or left in abeyance. Given the huge sums of money involved in these leagues/events, there are bound to be more than a few stakeholders hoping to cut their losses. This could potentially open the floodgates to litigation and a host of contractual disputes. This paper shall delve into potential defences that a party may rely upon in its attempts to defeat such litigious action. Specifically, this paper focuses on the English common law doctrine of frustration, the foundational theories behind it as well as the Indian iteration of this doctrine. The author also scrutinizes the concept of force majeure' and the potential of modern day force majeure' clauses to combat the issue at hand, and in doing so, illustrates how contractual disputes along these lines could influence the legal framework of sports contracts in the future
