Incorporation of a hybrid cooling system in water cooled power stations to reduce water and energy consumptions

Water shortage is a major problem facing the power industry in many nations around the world. The largest consumer of water in most power plants is the wet cooling tower. To assist water and energy saving for thermal power stations using conventional evaporative wet cooling towers, a hybrid cooling system is proposed in this paper. The hybrid cooling system may consists of all or some of an air pre-cooler, heat pump, heat exchangers, and adsorption chillers together with the existing cooling tower. The hybrid cooling system described in the paper, consisting of a metal hydride heat pump operating in conjunction with the existing wet cooling tower, is capable of achieving water saving by reducing the temperature of warm water entering the cooling tower. Cooler inlet water temperatures effectively reduce the cooling load on existing towers. This will ultimately reduce the amount of water lost to the air by evaporation whilst still achieving the same cooling output. At the same time, the low grade waste energy upgraded by the metal hydride heat pump, in the process of cooling the water, can be used to replace the bleed of steam for the lower stage feed heaters which will increase overall cycle efficiency.

Wireless sensor networks for in-situ image validation for water and nutrient management

Water and Nitrogen (N) are critical inputs for crop production. Remote sensing data collected from multiple scales, including ground-based, aerial, and satellite, can be used for the formulation of an efficient and cost effective algorithm for the detection of N and water stress. Formulation and validation of such techniques require continuous acquisition of ground based spectral data over the canopy enabling field measurements to coincide exactly with aerial and satellite observations. In this context, a wireless sensor in situ network was developed and this paper describes the results of the first phase of the experiment along with the details of sensor development and instrumentation set up. The sensor network was established based on different spatial sampling strategies and each sensor collected spectral data in seven narrow wavebands (470, 550, 670, 700, 720, 750, 790 nm) critical for monitoring crop growth. Spectral measurements recorded at required intervals (up to 30 seconds) were relayed through a multi-hop wireless network to a base computer at the field site. These data were then accessed by the remote sensing centre computing system through broad band internet. Comparison of the data from the WSN and an industry standard ground based hyperspectral radiometer indicated that there were no significant differences in the spectral measurements for all the wavebands except for 790nm. Combining sensor and wireless technologies provides a robust means of aerial and satellite data calibration and an enhanced understanding of issues of variations in the scale for the effective water and nutrient management in wheat.

Water and ion channels : crucial in the initiation and progression of apoptosis in central nervous system?

Programmed cell death (PCD), is a highly regulated and sophisticated cellular mechanism that commits cell to isolated death fate. PCD has been implicated in the pathogenesis of numerous neurodegenerative disorders. Countless molecular events underlie this phenomenon, with each playing a crucial role in death commitment. A precedent event, apoptotic volume decrease (AVD), is ubiquitously observed in various forms of PCD induced by different cellular insults. Under physiological conditions, cells when subjected to osmotic fluctuations will undergo regulatory volume increase/decrease (RVI/RVD) to achieve homeostatic balance with neurons in the brain being additionally protected by the blood-brain-barrier. However, during AVD following apoptotic trigger, cell undergoes anistonic shrinkage that involves the loss of water and ions, particularly monovalent ions e.g. K+, Na+ and Cl-. It is worthwhile to concentrate on the molecular implications underlying the loss of these cellular components which posed to be significant and crucial in the successful propagation of the apoptotic signals. Microarray and real-time PCR analyses demonstrated several ion and water channel genes are regulated upon the onset of lactacystin (a proteosomal inhibitor)-mediated apoptosis. A time course study revealed that gene expressions of water and ion channels are being modulated just prior to apoptosis, some of which are aquaporin 4 and 9, potassium channels and chloride channels. In this review, we shall looked into the molecular protein machineries involved in the execution of AVD in the central nervous system (CNS), and focus on the significance of movements of each cellular component in affecting PCD commitment, thus provide some pharmacological advantages in the global apoptotic cell death.

Reclaiming spent liquor from cotton reactive dyebaths using nanofiltration membrane for possible reuse of water and salt

During dyeing, salts are placed in a dyebath to aid the fixation of various dyes on to the fabric while bases are added to raise the pH from around neutral to pH 11. Afterwards, the used dyebath solution, called dyebath spent liquor, is discharged with almost all the salts and bases added as well as unfixed dyes. Consequently, a lot of raw materials are lost in the waste stream ending up in the environment as pollutants. In this study, possibilities of reusing water and salts of dyebathes were investigated, using a nanofiltration membrane. When the salt concentration in the spent liquor was increased from 10 to 80 g/L, the salt rejection by membrane was found to decrease initially; however, the salt rejection increased over the time, which was not expected. The aggregation of dye was also studied and found to decrease in the concentrate when the salt concentration was increased. This may be due to the aggregation of salt in the concentrate, which explains the increase in salt rejection. This information is useful for the textile industry in evaluating the treated water quality for the purpose of reuse.

Nanofiltration for the possible reuse of water and recovery of sodium chloride salt from textile effluent

During the reactive dyeing of cotton, salts such as sodium chloride (NaCI) are placed in a dyebath to aid the exhaustion of various dyes onto the fabric while bases are added to raise the pH from around neutral to pH 11 to achieve fixation. Afterwards, the used dyebath solution, called dyebath spent liquor, is discharged with almost all the salts and bases added as well as unfixed dyes. Consequently, many raw materials are lost in the waste stream ending up in the environment as pollutants. In this study possibilities of reusing the water and salts of dyebaths were investigated using a nanofiltration membrane. When the NaCI concentration in the spent liquor was increased from 10 to 80 g/L, the NaC1 rejection by the membrane was found to decrease initially; however, the NaC1 rejection increased over time, which was not expected. The aggregation of dye was also studied and found to decrease in the concentrate when the salt concentration was increased. This information is useful for the textile industry in evaluating the treated water quality for the purpose of reuse.