Journal of Energy Engineering

In this paper, a data-mining approach for modeling pumps in the wastewater preliminary treatment process is discussed. Data-mining algorithms are utilized to develop pump performance models based on industrial data collected at a municipal wastewater processing plant. The performance of wastewater pumps is described by two parameters, pump energy consumption and water flow rate after the pumps. Two types of models, dynamic and steady state, are established to predict pump energy consumption and water flow rate. The first type of model is developed based on 5-min data and the second type is built based on 30-min data. The accuracy of the models has been validated.

The United Arab Emirates (UAE) is an oil-rich country located in the eastern part of the Arabian Peninsula. Abu Dhabi is the largest emirate in the country, and Abu Dhabi is the capital of the UAE. The country has the one of the highest per capita rates of ${\mathrm{CO}}_2$ emission and water consumption in the world. Most of the water consumed is produced in desalination plants, which are energy intensive. The leadership of the country has made the bold decision to establish a renewable energy (RE) sector to diversify its energy sources and the economy as a whole. The Masdar Initiative was established to promote this objective. The government has established its first RE policy; the goal is to have 7% of power come from RE sources and technologies by 2020. This paper highlights the different RE projects of the Masdar Initiative, with particular emphasis on the power sector, and examines the new concentrated solar power (CSP) plants developed as part of the initiative.

A numerical procedure is developed for solving transient, three-dimensional heat-transfer problems of space cooling by using cold water flowing during the night within regularly arranged pipes, embedded in the ceiling within a layer of phase change material (PCM). Such systems are advantageous over the usual ceiling cooling systems because (1) the PCM layer may store considerably greater amounts of heat than those stored in the concrete slab, and (2) night cooling takes place under reduced electricity prices and meets the requirement of smoothing out electricity consumption by reducing daily peak loads. To simulate the phase change process, the concept of effective thermal capacity function is used, which is determined experimentally and then generalized by using triangular functions. Tests are also made with related functions given in the literature. The predictions of this study showed that the use of night ceiling cooling systems with PCM-embedded piping may offer energy savings and more thermal comfort than systems without PCM, even in cases in which system parameters do not permit the user to take advantage of the entire PCM storage capacity. The developed numerical procedure may be used for defining, in each case, the proper values of the system parameters to completely take advantage of the PCM storage capacity.

This paper presents the characteristics of a power plant that combines renewable energy sources (RES), that is, a photovoltaic (PV) power plant and pump storage hydroelectric (PSH), to achieve sustainable production of green electric energy equal to that of conventional energy sources. The proposed solution does not produce ${\mathrm{CO}}_2$ and does not significantly use freshwater or other resources. The PSH storage is the main element of the proposed power plant system, which provides a continuous and reliable supply of green energy. Its size significantly affects the size of the PV generator and operation characteristics of the hybrid plant. The paper elaborates in detail the functional relationship between the choice of the PV generator power and the PSH upper storage volume and presents the basic mathematical relations. The algorithm of the system development is presented, along with the procedure choice solutions. The results from the case study show that the concept is flexible in design, construction, and operation.

A numerical simulation is carried out to investigate the effect of inlet port cross-section geometry on the in-cylinder flow of a motored four-valve, single-cylinder, four-stroke internal combustion engine during the intake and compression strokes. The simulation is performed by solving the three-dimensional time-dependent compressible RANS equations in conjunction with the standard $k-\epsilon$ turbulence model using the commercial CFD software STAR-CD. To simulate the reciprocating piston motion, the governing equations are solved on a multiblock unstructured moving mesh. Two inlet port cross-section geometries are considered in the present study: circular cross section and elliptical cross section. The emphasis of the present study is on the tumble motion. The evolution of the flow structure and the quantified strengths of the tumble motions, namely, tumble ratio and cycle-averaged tumble ratio in the symmetry and offset planes for the two cases, are presented. It is found that inlet port with elliptical cross-sectional area is more conducive to tumble motion.

Following such natural disasters as Hurricanes Katrina and Ike and the 2010 Haiti earthquake, supplying a reliable source of clean drinking water has apparently become essential. Providing a water supply and the associated transportation of potable water is a considerable burden on recovery efforts following a natural disaster. To reduce this burden and meet the water requirements of a community, a low-maintenance, low-cost trailer-mounted water disinfection system has been developed that has the capability to provide potable water from local surface water bodies until the infrastructure is repaired. To achieve disinfection of contaminated surface water, the system uses a series of prefilters and an ultraviolet (UV) disinfection unit. The system is powered using a hybrid photovoltaic array and wind turbine system. To increase the storage capability and decrease the maintenance required by the system, traditional, relatively high-maintenance batteries have been replaced with an ultracapacitor to store the energy generated by the renewable energy component. The prototype system was field tested for several months. Tests conducted on the system included monitoring the energy generation and consumption of system components and verification of the disinfection capability by sampling various surface water bodies. The prototype performed as desired; however, during testing the PV array provided sufficient energy and the wind turbine was deemed redundant.

Latent heat storage systems can improve the energy use efficiency and conserve limited energy resources. Microcapsules of lauric acid (LA) as the core and melamineformaldehyde (MF) resin as the shell were prepared as phase change material for latent heat thermal storage by in situ polymerization. The obtained microcapsules were characterized in their surface morphology, particle sizes, thermal properties, thermal cycling, and heat insulation test. Scanning electron microscope analysis suggests that the obtained microcapsules have a spherical shape and smooth surface, and the shell material presents a round shell layer associated with an inner porous structure. Differential scanning calorimeter measurement indicates that the fusion enthalpy of encapsulated LA is $84.96\mathrm{J}/\mathrm{g}$, which corresponds to 46.2% by weight of core content. The accelerated thermal cycling test proves that the melting temperature of encapsulated LA has little change after 70 thermal cycles. The heat insulation test indicates that LA microcapsules mixed with acrylic latex coating as a kind of smart coating can reduce the indoor temperature fluctuations. The preceding results showed that the MF/LA microcapsules possess good potential as a latent heat storage material.