J. A. López Ramírez

Bio: J. A. López Ramírez is an academic researcher from University of Cádiz. The author has contributed to research in topics: Fouling & Reverse osmosis. The author has an hindex of 1, co-authored 1 publications receiving 1 citations.

A methodology for non-invasive diagnosis of diesel engines through characteristics of starter system performance

Abstract: In this work, a methodology to diagnose ten diesel bus engines is carried out by means of some characteristics of the starting system performance. The signals of battery voltage, electric current supplied to the starter motor and crankshaft revolutions during cold and warm engine starting processes are analysed. Characteristics and patterns of the signals that are attributable to engine compression and combustion failures are pointed out, which are related to the kilometres travelled by each vehicle after the last engine repair and the shutdown time of the engine in warm condition. It is obtained that the rise of the current required by the starter motor during the second and third compression process, and the mean crankshaft angular acceleration after the second compression process are characteristics that are related to the engine condition.

Optimization of the Sequence of Washing Reverse Osmosis Membranes Used for Seawater Desalination

Abstract: Seawater contains a number of organic and inorganic components that cause fouling of membranes when subjected to a process of reverse osmosis desalination. This fouling is one of the most important problems in the management of desalination plants, as it entails a significant loss in system performance. For membranes to be able to continue operating under appropriate conditions, they must undergo periodic cleaning protocols. This paper presents the results obtained when, subjecting a previously fouled aromatic polyamide membrane to different washing agents and using different concentrations of the same. Optimal concentrations of cleaning reagents were established. The results indicate that the performance of cleaning using a mixture of reagents, and alternating alkaline and acidic media, enabled maximum recovery of the membrane permeate flux (94.2 %) and a significant reduction in the consumption of cleaning reagents.

Effective Antiscaling Performance of Reverse-Osmosis Membranes Made of Carbon Nanotubes and Polyamide Nanocomposites

Abstract: The antiscaling properties of multiwalled carbon nanotube (MWCNT)–polyamide (PA) nanocomposite reverse-osmosis (RO) desalination membranes (MWCNT–PA membranes) were studied. An aqueous solution of calcium chloride (CaCl2) and sodium bicarbonate (NaHCO3) was used to precipitate in situ calcium carbonate (CaCO3) to emulate scaling. The MWCNT contents of the studied nanocomposite membranes prepared by interfacial polymerization ranged from 0 wt % (plain PA) to 25 wt %. The inorganic antiscaling performances were compared for the MWCNT–PA membranes to laboratory-made plain and commercial PA-based RO membranes. The scaling process on the membrane surface was monitored by fluorescence microscopy after labeling the scale with a fluorescent dye. The deposited scale on the MWCNT–PA membrane was less abundant and more easily detached by the shear stress under cross-flow compared to other membranes. Molecular dynamics simulations revealed that the attraction of Ca2+ ions was hindered by the interfacial water layer f...

Voltage Signals Measured Directly at the Battery and via On-Board Diagnostics: A Comparison

Abstract: Nowadays, cars are an essential part of daily life, and failures, especially of the engine, need to be avoided. Here, we used the determination of the battery voltage as a reference measurement to determine possible malfunctions. Thereby, we compared the use of a digital oscilloscope with the direct measurement of the battery voltage via the electronic control unit. The two devices were evaluated based on criteria such as price, sampling rate, parallel measurements, simplicity, and technical understanding required. Results showed that the oscilloscope (Picoscope 3204D MSO) is more suitable for complex measurements due to its higher sampling rate, accuracy, and versatility. The on-board diagnostics (VCDS HEX-V2) is more accessible to non-professionals, but it is limited in its capabilities. We found that the use of an oscilloscope, specifically the Picoscope, is preferable to measure battery voltage during the engine start-up process, as it provides more accurate and reliable results. However, further investigation is required to analyse numerous influences on the cranking process and the final decision for the appropriate measurement device is case specific.

Voltage Signals Measured Directly at the Battery and via On-Board Diagnostics: A Comparison

Abstract: Nowadays, cars are an essential part of daily life, and failures, especially of the engine, need to be avoided. Here, we used the determination of the battery voltage as a reference measurement to determine possible malfunctions. Thereby, we compared the use of a digital oscilloscope with the direct measurement of the battery voltage via the electronic control unit. The two devices were evaluated based on criteria such as price, sampling rate, parallel measurements, simplicity, and technical understanding required. Results showed that the oscilloscope (Picoscope 3204D MSO) is more suitable for complex measurements due to its higher sampling rate, accuracy, and versatility. The on-board diagnostics (VCDS HEX-V2) is more accessible to non-professionals, but it is limited in its capabilities. We found that the use of an oscilloscope, specifically the Picoscope, is preferable to measure battery voltage during the engine start-up process, as it provides more accurate and reliable results. However, further investigation is required to analyse numerous influences on the cranking process and the final decision for the appropriate measurement device is case specific.