Small engines as bottoming cycle steam expanders for internal combustion engines

Heat recovery bottoming cycles for internal combustion engines have opened new avenues for research into small steam expanders [1]. Dependable data for small steam expanders will allow us to predict on their suitability as bottoming cycle engines and the fuel economy achieved by using them as bottoming cycles. Wankel Engines, with its lower resistance properties at small scale provide excellent contenders for bottoming cycle expanders. Present paper is based on results of experiments carried out on small scale Wankel and two stroke reciprocating engines as air expanders and as steam expanders. A test facility developed at Sussex used for measurements comprised of a torque, power and speed measurements, electronic actuation of valves, synchronized data acquisition of pressure and temperatures of steam and inside the engines for steam and internal combustion cycles. Results are presented for four engine modes, viz. reciprocating engine in uniflow steam expansion mode and air expansion mode, and rotary Wankel engine in steam expansion mode and air expansion mode. The air tests will provide base data for friction and motoring effects whereas steam tests will tell how effective will the engines be in this mode. Results for power, torque, and p-V diagrams are compared to determine the change in performance from air expansion mode to steam expansion mode

Small-Scale Compressed Air Energy Storage Application for Renewable Energy Integration in a Listed Building

In the European Union (EU), where architectural heritage is significant, enhancing the energy performance of historical buildings is of great interest. Constraints such as the lack of space, especially within the historical centers and architectural peculiarities, make the application of technologies for renewable energy production and storage a challenging issue. This study presents a prototype system consisting of using the renewable energy from a photovoltaic (PV) array to compress air for a later expansion to produce electricity when needed. The PV-integrated small-scale compressed air energy storage system is designed to address the architectural constraints. It is located in the unoccupied basement of the building. An energy analysis was carried out for assessing the performance of the proposed system. The novelty of this study is to introduce experimental data of a CAES (compressed air energy storage) prototype that is suitable for dwelling applications as well as integration accounting for architectural constraints. The simulation, which was carried out for an average summer day, shows that the compression phase absorbs 32% of the PV energy excess in a vessel of 1.7 m(3), and the expansion phase covers 21.9% of the dwelling energy demand. The electrical efficiency of a daily cycle is equal to 11.6%. If air is compressed at 225 bar instead of 30 bar, 96.0% of PV energy excess is stored in a volume of 0.25 m3, with a production of 1.273 kWh, which is 26.0% of the demand

Examination of the coatings of coronary stents

In our study the main properties of coated coronary stents are shown, such as foreshortening, recoil, surface features and failures and the expansion properties. The types and the effects of active and passive coatings are introduced. The results of our examinations with different coated coronary stents are shown as well

Detector for inspection of fire alarms

Portable detector tests rate-of-rise temperature devices. Incandescent light bulb is calibrated to produce rate of temperature rise necessary to activate properly functioning alarm

Improved reversible coulometer cell

Cell operates either as timer or current-time integrating device in any physical orientation with better than 2 percent accuracy over temperature range of 283 K to 398 K, with input current range from few microamperes to approximately 1000 microamperes over time period of 1 sec to several hours

Numerical Modelling and Experimental Validation of Twin-Screw Expander

Positive displacement machines have been identified as appropriate expanders for small-scale power generation systems such as Organic Rankine Cycles (ORCs). Screw expanders can operate with good efficiency in working fluids under both dry and two-phase conditions. Detailed understanding of the fluid expansion process is required to optimise the machine design and operation for specific applications, and accurate design tools are therefore essential. Using experimental data for air expansion, both CFD and chamber models have been applied to investigate the influence of port flow and leakage on the expansion process. Both models are shown to predict pressure variation and power output with good accuracy. The validated chamber model is then used to identify the optimal volume ratio and rotational speed for experimental conditions

Development and Examination of Coated Coronary Stents

The aim of this study is to show the developments carried out by us with coated stents, expansion properties, furthermore the failures of the coatings. The coating was examined before and after expansion, paying special attention to the curves. The quality and the changing of the coatings were examined by different methods: optical microscopy, atomic force microscopy, scanning electron microscopy and EDS analysis. The results show that the expansion to a higher pressure did not change the coating. Polyurethane coating was given to TentAur stents. The coatings were produced by a method of dipping. The sterile and dust free environment is crucial to produce a suitable coating. Electro-polished and non-electro-polished sheets and stents were used for these experiments. The quality and the changing of the coatings were examined by different methods after drying. The fatigue tests showed that the polyurethane coating had suitable adherence