Effect of Operational and Design Parameters on Desiccant-Assisted Hybrid Air-conditioning Systems Performance

Energy savings are a major goal in our lives because energy consumption is continuously increasing. We have studied in this paper four air conditioning systems, so that each system mainly consists of a vapor compression cycle and a rotating desiccant wheel. The thermodynamic analysis for air conditioning system, the heat exchanger, the ground heat exchanger and the evaporative water spray cooler were presented. Design and operating parameters including outlet air temperature, outlet air humidity, regeneration air temperature, and desiccant wheel speed are studied to assess its effect on the performance of the systems considered. This hybrid system significantly decreases the supplied air temperature at different four Systems. When the inlet air humidity ratio and the regeneration air temperature increase, the COPth of the air conditioning system decreases. When the desiccant wheel speed increased, the COPth of the air conditioning system decreases. COPth decreases with the increasing of the cooling load for the space and also decreases with the decreasing of the inlet air humidity ratio at process air. The results show that in these four systems, COPth is the highest at system 4 which contains desiccant wheel, heat exchanger and ground source circulation achieving an improvement of about 48 % and a consequent power consumption reduction of 20 %

Thermal Analysis of a Hybrid Air Conditioning System with Geothermal Energy

Hybrid air conditioning systems can allow significant energy saving and emissions reductions with respect to conventional air-conditioning systems. Thermal analysis of a desiccant wheel, a heat exchanger, a ground source circulation system, and a solar collector for a hybrid air conditioning system is performed in this study. The effects of these parameters have been studied: Inlet air temperature, Inlet air humidity ratio, wheel speed, regeneration temperature, regeneration mass flowrate, heat exchanger effectiveness, ground source circulation effectiveness, and solar radiation on the behavior of the outlet air temperature and the outlet air humidity ratio from the desiccant wheel, the area of solar air collector, the solar collector efficiency, the cooling coil load, and the coefficient of performance. The hybrid system is more efficient than the vapor compression system. The hybrid system significantly decreases the cooling coil load, the cooling coil load of the hybrid system is approximately 48 % lower than the vapor compression system

COMPARATIVE STUDY ON THE ENERGY CONSUMPTION OFUNDERFLOOR HEATING SYSTEM UTILIZING DIFFERENT PCM

The most global energy that directly related to building sector is the amount of energy consumption in the heating, and air-conditioning. One of the best ways that that enhances the reduction of this energy consumption and maintains the best comfort zone to the occupant is using a phase change material (PCM) with under floor heating/cooling system. In the present work, a new theoretical study involving comparative investigation among different PCMs on the energy consumption of under floor heating system has been performed. The most used organic and inorganic PCMs complete with their specified thermos-physical properties with the melting temperature as the main effective properties are studied. In addition, economical studies for all selected PCMs have been performed. Therefore, the finest PCM is selected carefully to satisfy law energy consumption with low cost. The results show that the organic PCM A39 with melting temperature of 39 °C is suggested the optimum as it has less negative effect on the environment with high power saving. The Cacl2-6H2O PCM is recommended with the restrictions of the impacts on the environments due to the low cost. In addition, it is found that the thickness of the PCM has a remarkable effect on the law energy consumption and so, the small thickness is recommended to give low cost. Unlike using PCM in roofs and walls, in underfloor heating system application PCM melting temperature should be suitable for floor surface temperature and room air temperature

Performance and enhancement evaluation of a solar still by using spraying technology

The current experimental investigation uses the water spraying approach to increase the productivity and efficiency of pyramid solar still. The design, construction, and testing of a traditional and modified small-scale pyramid solar still were conducted under identical meteorological conditions as in Tanta City, Egypt (30° 47\u27 N, 31°E). One of the modifications is that heated sheet metal will occasionally be sprayed with salted water. We looked into how the modified solar still\u27s (MPSS) performance characteristics were affected by solar radiation, water depth, and sheet metal-specified temperature. Measurements were made of the saline water temperature, glass temperature, spraying flow rate, and daily productivity. The performance of MPSS and traditional pyramid solar stills (CPSS) was contrasted. Because the results indicated that water depth had a detrimental impact on productivity, we chose the lowest level that could be achieved—roughly 15 mm for MPSS and 8 to 22 mm for CPSS. For MPSS and CPSS, the daily productivity was approximately 5000 ml/m2 and 2830 ml/m2, respectively. MPSS outperformed CPSS in productivity by almost 44 %. Furthermore, the modified pyramid solar daily efficiency ranges from 57 to 69%, while the regular pyramid solar still ranges from 26 to 41%

FACTORS AFFECT PERFORMANCE MEASUREMENT IN CONSTRUCTION PROJECT PORTFOLIO

Construction companies regularly perform multiple construction projects concurrently. Projects vary by complexity, duration, budget, variety of works, and the number of stakeholders. To determine and report the status of the ongoing portfolio of projects, methodical agreed-upon metrics should be set forth at both projects and portfolio level. The assessment of project indicators during implementation is not an easy task due to the lack of up-to-date data and factors measuring problems. The purpose of the research is to analyze common performance measurement factors, the contribution of those factors to the overall project portfolio performance, and to illustrate how to assess a projects' execution efficiency. A review for the earlier research and studies has been done to name the commonly used factors usually picked to measure the performance of portfolio and project management efficiency. A questionnaire survey conducted to project management professionals exploring their judgment in respect of relative weight contribution to each factor. AHP mathematical model used to analyses the survey responses

Performance Enhancement of Reverse Osmosis (RO) Membrane Using Nanocomposite Materials

Many attempts were made to enhance the performance of reverse osmosis (RO) membranes in the desalination process. Using ion exchange (IX) bed before RO process and modifying the structure of RO membranes are some of these attempts. Thin film nanocomposite (TFN) membrane is the novel type of RO membranes which is the best in nanofiltration applications. TFN membranes have many new advantages due to the change of their structure in comparison with traditional membranes. In this study the performance of a TFN membrane was compared with that of standard thin film composite (TFC) spiral wound water desalination RO membrane for filtration of IX produced water. The results from the filtration process showed that the flux and water permeability of TFN are 1.55 and 1.56 times that of TFC for feed water with 2050 ppm NaCl concentration with nearly unchanged level of the membrane salt rejection, which will reduce the filtrated water cost

Developing Framework to Optimize the Preparation of (EOT) Claims Using Integration of (LPS) and (BIM) Techniques in Construction Projects

Construction projects face delays and disturbances that could be caused by one of the contracting parties, both of them, or beyond their control. Proving the delay needs a significant effort to introduce all details, documents, and records which explain the causes of the delays. The contractor needs to submit a claim, whether it is extension of time (EOT) claim or any claim with an adequate definition, causation, liabilities, analysis of delays to get an extension of time-related to the risk event. Claims preparation processes need to be collected and documented daily throughout the project phases, especially during construction phases. Lean Construction, with its common technique, the last planner system (LPS), and building information modeling (BIM) have significant synergies and can bring benefits when implemented together to support the preparation of the extension of time (EOT) claim. Building information modeling used as a digital platform to facilitate communication between the project team, improve project performance, and implement the last planner system (LPS) phases effectively. (LPS) is enhancing the coordination within the project team. The primary purpose of the research is to develop Framework to Optimize the preparation of extension of time (EOT) Claims Using Integration of the last planner system (LPS) and building information modeling (BIM) Techniques in Construction Projects. The integration will represent in implementation of the appropriate (BIM) functionalities along with the five phases of the last planner system (LPS). As a result of the integration, the inputs and outputs well documented, which considered as the primary support to the processes preparation of the extension of time (EOT) claim. Also, The framework supported by process flowchart to clarify outputs, inputs, and the project team's responsibility, Which will contribute to optimizing the preparation of the extension of time (EOT) claims

Heat Transfer Performance of a Gasketed Plate Heat Exchanger Subjected to Mechanical Vibration

Heat transfer characteristics in terms of heat transfer coefficient, overall heat transfer coefficient and heat exchanger effectiveness of a vertical counter flow Gasket plate heat exchanger (GPHE) are experimentally investigated. The tested PHE is made of stainless-steel plates with 30° chevron angle (β=30°). The surface enlargement factor, Ф for all plates was 1.17. Six plates were installed; providing two hot channels and three cold channels in counter flow arrangement. The vibration effect on tested GPHE has been performed and compared with non-vibration model. Vibration frequencies (ω) are in the range of 13.33 to 46.67 cps and vibrational dimensionless amplitude (A/De) varied from 9.14*10-3 to 52.66*10-3 at various oscillating Reynolds numbers were employed. It is found that the heat transfer performance of the GPHE is enhanced when vibration is applied. The maximum enhancement percentage of the GPHE heat transfer coefficient, overall heat transfer coefficient and effectiveness due to vibration are 43%, 31% and 18%, respectively. These maximums are occurred at oscillation Reynolds number of 211.34 and A/De = 52.66*10-3 which after the resonance condition. The GPHE performance after and before resonance condition are obtained. Finally, correlations for GPHE Nusselt number, when vibration is and is not applied, are obtained with an acceptable error of 3.99%

Topical Oxybutynin 3% Gel versus Aluminum Chloride 15% Lotion in Treatment of Primary Focal Hyperhidrosis

Introduction: Hyperhidrosis is excessive sweating beyond thermoregulatory needs. It is a potentially disabling condition with challenging management. Aluminum chloride is the established topical treatment; however, response remains unsatisfactory. Oxybutynin is an anticholinergic drug that stands as a therapeutic chance for hyperhidrosis. Objectives: comparing the efficacy of topical oxybutynin 3% gel versus aluminum chloride 15% lotion in treatment of primary focal hyperhidrosis. Methods: Forty patients with hyperhidrosis were randomly distributed into 2 equal groups treated by either topical oxybutynin 3% gel or topical aluminum chloride 15% lotion once daily night application for 4 weeks (both groups). Evaluation was done at 2 and 4 weeks of treatment and after 1 month of the end of treatment for follow up by Minor iodine starch test, hyperhidrosis disease severity scale (HDSS) and dermatology life quality index (DLQI). Results: Both treatment modalities were effective with insignificant differences between patients of both groups regarding improvement in Minor iodine starch test and HDSS after 2 weeks of treatment (P = 0.561, 0.33 respectively). Oxybutynin 3% gel yielded significantly better improvement of Minor’s test, HDSS and patient’s quality of life at the end of 4 weeks of treatment with lower recurrence rate than aluminum chloride 15% lotion at 1 month follow up. Minimal adverse effects were noted in both studied groups. Conclusions: Oxybutynin 3% gel could be considered as a promising treatment modality for hyperhidrosis with higher efficacy than aluminum chloride 15% lotion and lower recurrence rate