Search results for "Fouling"

Getting insights into the behavior of variable speed direct expansion air conditioning systems under faulty operating conditions

2019

Direct expansion air conditioning systems, such as rooftop units, are widely adopted in small and medium scale commercial buildings. In order to increase the energy performance of these systems during part-load operation, variable-speed compressors and fans have been adopted in the last two decades. However, profitable energy saving could be achieved not only by optimizing the design and the control of these systems, but also by scheduling a proper maintenance strategy. In fact, if not properly maintained, no benefits would be achieved even when more sophisticated systems are adopted. In order to support plant owners in scheduling cost-effective maintenance program, Fault Detection and Diag…

Biological minimization of excess sludge in a membrane bioreactor: Effect of plant configuration on sludge production, nutrient removal efficiency an…

Assessing the Robustness of Thermoeconomic Diagnosis of Fouled Evaporators: Sensitivity Analysis of the Exergetic Performance of Direct Expansion Coi…

2016

Thermoeconomic diagnosis of refrigeration systems is a pioneering approach to the diagnosis of malfunctions, which has been recently proven to achieve good performances for the detection of specific faults. Being an exergy-based diagnostic technique, its performance is influenced by the trends of exergy functions in the “design” and “abnormal” conditions. In this paper the sensitivity of performance of thermoeconomic diagnosis in detecting a fouled direct expansion coil and quantifying the additional consumption it induces is investigated; this fault is critical due to the simultaneous air cooling and dehumidification occurring in the coil, that induce variations in both the chemical and th…

Performance maps for an air-cooled air conditioning system as a preliminary instrument for the diagnosis of evaporator fouling

2019

Abstract During the past few decades, there has been increased interest in the development of automated approaches for detecting and diagnosing faults in air conditioning systems. Among them, thermoeconomic diagnosis is a technique which involves the use of exergy analysis. As a first step towards improving its performance, this work is focused on the thermodynamic and exergy analysis of a direct expansion air conditioning system used in small commercial building applications. The analysis was carried out by means of experimental activities on a 17.5 kW rooftop unit installed at the Herrick Laboratories, Purdue University, Indiana (USA). The system under investigation was equipped with a va…

Self-cleaning antimicrobial surfaces by bio-enabled growth of SnO2 coatings on glass.

2013

Conventional vapor-deposition techniques for coatings require sophisticated equipment and/or high-temperature resistant substrates. Therefore bio-inspired techniques for the fabrication of inorganic coatings have been developed in recent years. Inspired by the biology behind the formation of the intricate skeletons of diatoms orchestrated by a class of cationic polyamines (silaffins) we have used surface-bound spermine, a naturally occurring polyamine, to promote the fast deposition of homogeneous, thin and transparent biomimetic SnO2 coatings on glass surfaces. The bio-enabled SnO2 film is highly photoactive, i.e. it generates superoxide radicals (O2˙(-)) upon sunlight exposure resulting i…

Catalytic hydrothermal liquefaction of municipal sludge assisted by formic acid for the production of next-generation fuels

2021

Abstract Hydrothermal liquefaction (HTL) of municipal sludge (MS) was studied at 325 °C and 30 min at 10 and 30% w/w concentration of MS using formic acid (FA) as a green liquid hydrogen donor both in the absence and in the presence of heterogeneous catalysts. Pellets of commercial NiMo/Al2O3, CoMo/Al2O3 and felt of activated carbon ACF 1600 were used as catalysts. The addition of FA at high MS loading allowed to increase the yields in BC from 41 to 62% and its H/C ratio from 1.80 to 2.01 leading to energy recovery (ER) higher than 100%.When heterogeneous catalysts were used together with FA, a marked improvement of BC yields and quality was obtained at 10% MS loading. This behavior was not…

Enzyme recovery and fouling mitigation by ultrasound-enhanced ultrafiltration

2013

Abstract The development of second-generation biofuels from cellulosic/lignocellulosic biomass has advantages from energy and environmental aspects, but the overall cost of the process is mainly dependent on the cost of the enzymes. Enzyme recovery and recycling is one of the most important and effective means of increasing the efficiency of enzymatic hydrolysis processes by lowering the enzyme costs. The primary objective of this study was to investigate the possibilities of enzyme recovery by membrane separation. Ultrafiltration (UF) membranes with various cut-off values and materials were used to recycle cellulase and cellobiase in model solutions and cellulosic hydrolysates. The membran…

Cerdioxid schützt vor marinem Fouling

2017

Demethanization of aqueous anaerobic effluents using a polydimethylsiloxane membrane module: Mass transfer, fouling and feasibility

2017

Abstract The performance, fouling and feasibility of a polydimethylsiloxane hollow fibre membrane module for in situ methane degasification from the effluent of an Expanded Granular Sludge Bed anaerobic reactor has been investigated. Experiments at different operational conditions were carried out (liquid flow, sweep gas flow and vacuum pressure) with maximum removal efficiency (77%) at lowest flow-rate (0.4 L h−1), highest vacuum gauge pressure (−800 mbar) and liquid flowing in lumen side. Mass transport analysis denoted a considerably higher methane transfer than that predicted (attributed to liquid oversaturation). An enhancement factor for liquid phase has been proposed to correlate the…

Nanofiltration of secondary effluent for wastewater reuse in the textile industry

2008

Abstract Textile industries represent an important environmental problem due to their high water consumption. In many Spanish regions with water scarcity, this fact can be an argument to make wastewater reuse necessary. In this work, a biologically treated wastewater from a cotton thread factory was subjected to nanofiltration (NF) in two ways, direct NF treatment and NF after a pre-treatment stage by ultrafiltration (UF). Nowadays, the factory effluent is treated by an activated sludge process. This effluent has high values of COD (200mgO 2 L −1 ) and TDS (5000mg L −1 ) which makes its use in the textile processes impossible. In such situations, reverse osmosis (RO) has been typically used…