DOUBLE PERFORATED IMPINGEMENT PLATE (DPIP) IN SHELL-AND-TUBE HEAT EXCHANGER

This paper presents a solution to a chronic problem causing repeated tube failure at shell-and-tube heat exchangers. The problem is related to fouling process on tubes surface which accumulates downstream the impingement plate at exchanger inlet nozzle within the first tube rows due to low velocity and vortices production. In fouling services, the suspended deposits, fouling, accumulates on tubes surface downstream the impingement plate causing under-deposit corrosion and raising tubes surface temperature due to lack of cooling accelerating fouling process. Under fouling corrosion attacks tubes and causes repeated tube failure costing a lot of money in terms of material, maintenance and production losses. Normal practice of extending tubes life and delaying their failure is to upgrade the tubes metallurgy. So this paper objective is to present an economical solution option through modifying the impingement plate in shell-and-tube heat exchangers where impingement plate is recommended by Tubular Exchanger Manufacturers Association, TEMA. The impingement modification is to replace the solid conventional impingement plate with double spaced plates having offset holes, called Double Perforated Impingement Plate (DPIP). The objective of this work can be met through simulate and compare shell side inlet flow distribution around the conventional and modified impingement plate, DPIP, and insuring of enhancing the flow pattern distribution at the area behind impingement plate. Since experimental work in flow investigation can be time consuming and costly, computational fluid dynamics, CFD, fluent software was implemented as a cost effective helpful tool to conduct the simulation and comparison purpose. The modified impingement plate, DPIP, will destroy vortices created behind the conventional plate retarding fouling accumulation principal. DPIP will enhance shell side flow distribution downstream the impingement plate and stop fouling accumulation on the tubes to prevent under-deposit corrosion

The Impact of Property Management on the Value of Residential Product in Saudi Arabia

This paper discusses the impact of property management in maintaining the value of residential product in Saudi Arabia. The paper reviewed a comparison of two property models: the first is managed by the property management system, and the second is managed by the owner only. In addition, the field questionnaire was used and distributed to a sample of the study community consisting of 125 real estate management institutions and real estate office in Riyadh. The results of the analysis indicate that property management contributes to raising the quality of the residential product and maintaining its market value. The residential product which managed by the property management system loses 10% of its value after 5 years. On the other hand, the product that managed by the owner loses more than 50% of its real value after 5 years. The paper proposes to strengthen cooperation between governmental and private institutions to establish a Real Estate Data Center (REDC) for the classification of residential properties subject to the criteria of management, quality and economic cost

Fear of the Unknown among Normal People, People with Psychological Disorders, and People with Organic Disorders in the Light of Some Demographic Variables

The present paper aimed to determine the fear of the unknown among normal people, people with psychological disorders, and people with organic disorders in the light of some demographic variables. The authors adopted the descriptive-comparative method and developed and applied a three-domain questionnaire to a randomly selected sample of (942) participants. The results showed that the people with psychological disorders suffer from fear of the unknown more than normal people and people with organic disorders at a significance level of (0.05). There were no statistically significant differences between the different categories of psychological disorders (including generalized anxiety disorder, depression, panic attacks, post-traumatic stress disorder, obsessive-compulsive disorder, and phobia) in contrast with the organic diseases, in which cardiac and respiratory diseases were at a greater risk of being afraid of the unknown more than those with diabetes, blood pressure, and thyroid. The paper recommends conducting further studies on the concept of fear of the unknown in the Arab countries and adopting fear of the unknown as a psychological intervention for people with psychological disorders and people with cardiac and respiratory diseases

Persistent hyperinsulinemic hypoglycemia of infancy: long-term follow-up after surgical treatment

Aim The aim of this study was to investigate the long-term outcome of six children with persistent hyperinsulinemic hypoglycemia of infancy (PHHI) after pancreatectomy who have been followed since 1990 at the Riyadh Military Hospital, Riyadh, Kingdom of Saudi Arabia.Patients and methods Data from six patients were retrospectively analyzed from chart review. PHHI was diagnosed on the basis of having high-insulin levels and low-glucose levels and a high insulin-to-glucose ratio. Lactate, pyruvate, ammonia, and urinary organic acid levels were recorded and tandem mass spectrometry screening was performed. The patients were assessed radiologically by MRI of the brain and by ultrasound examination of the abdomen. Patients who failed medical therapy underwent near-total pancreatectomy.Results Hypoglycemic convulsion was the most common presenting complaint. None of the patients responded to medical treatment and thus underwent surgery. Two patients still had hypoglycemic episodes after surgery, requiring medical treatment. However, they underwent subsequent surgery because of unresponsiveness to medical therapy. Three patients developed diabetes. None of them had malabsorption, and two patients later developed epilepsy.Conclusion The earlier the age at diagnosis, the better the neurological outcome. Delayed surgery might be associated with higher risk of development of diabetes. Near-total (90–95%) pancreatectomy is the treatment of choice for PHHI not responsive to medical treatment.Keywords: Near-total pancreatectomy, outcome, persistent hyperinsulinemic hypoglycemia of infanc

Microbial Contamination of Date Rutab Collected from the Markets of Al-Hofuf City in Saudi Arabia

The microbial contamination of 60 samples from six date cultivars in the rutab stage purchased from different retail outlets in AL-Hofuf City, Saudi Arabia was studied. All samples were found contaminated with aerobic mesophilic bacteria at loads in the order 102 to 105 cfu/cm2 with some significant differences among varieties that can be attributed to differences in the weather conditions during rutab season. Also all samples, except only one, were contaminated with molds and yeasts at loads in the order 102 to 103 cfu/cm2. Potentially pathogenic Staphylococcus aureus was detected in 57 samples and A. flavus/parasiticus in 13 samples, while coliforms were detected in 39 samples

Stability of Rock Slopes along Raidah Escarpment Road, Asir Area, Kingdom of Saudi Arabia

The Raidah Escarpment road is located north west of Abha city, Asir region, Kingdom of Saudi Arabia. This escarpment road represents an important corridor in the area which connects different villages and tourist resorts with each other. The total length of this road section is about 9 km which passes through a highly mountainous area. The road also passes through areas of different geological hazards (rock, debris flow, soil, and weathered zones). The different environmental factors (e.g. intensive rainy summer), variable geological and structural elements (weak rocks, slide debris weak soils, shear zones, and faults) difficult road characteristics (narrow roads with tight horizontal andvertical curvature) and various human activities in the area make the road susceptible to frequent slope failures (rockfalls, rock sliding, debris flow, soil slides, and raveling) from time to time. This paper deals with the evaluation of the stability of the rock cuts along the Raidah escarpment road using two methods including a structural controlled method and a raveling type method. Raidah escarpment rock cuts have been classified into sixty nine stations which were investigated and subsequently rated. Results of this study indicated that: (1) Based on the structiural control mode of failures, it was found that 12 stations are potentially unstable due to planar, wedge, and toppling failures, and out of them five stations have a major impact on the road in the event of failure, including stations 11, 17, 20, 31, and 40. (2) According to the Modified Colorado Rockfall hazard rating system, it was found that 13, 12, 13, 17, and 49 stations are of high, high to moderate, moderate, moderate to low, and low hazard. On the other hand, it was found that 13, 11, 11, and 69 stations have a high, high to moderate, moderate, and low impact on the road in the case of failure. (3) According to the field simulation tests it was found that 6 stations potentially show highly problems from rolling and bouncing rocks. However, out of these sites it was found that only 4 stations have a high impact on the road due to rolling and bouncing. (4) the areas that are impacted by the debris flows have been mapped and determined. Finally, different recommendations and remediation methods have been discussed to minimise the impact of problimatic sites

Experimental investigation on the impact of connate water salinity on dispersion coefficient in consolidated rocks cores during enhanced gas recovery by CO2 injection

Connate water salinity is a vital property of the reservoir and its influence on the displacement efficiency cannot be overemphasised. Despite the numerous analytical literatures on the dispersion behaviour of CO2 in CH4 at different parametric conditions, studies have so far been limited to systematic effects of the process while parameters such as connate water salinity of the reservoir has not been given much attention and this could redefine the CO2-CH4 interactions in the reservoir. This study aims to experimentally determine the effect of connate water salinity on the dispersion coefficient in consolidated porous media under reservoir conditions. A laboratory core flooding experiment depicting the detailed process of the CO2-CH4 displacement using Grey Berea sandstone core sample at a temperature of 50°C and at a pressure of 1300 psig was carried out to determine the optimum injection rate, from 0.2-0.5 ml/min, for the experimentation based on dispersion coefficients and methane recovery in the horizontal orientation. This was established to be 0.3 ml/min. At the same conditions, the effects of connate water saturation of 10% and a salinity of 0 (distilled water), 5, and 10% wt. with a CO2 injection rate of 0.3 ml/min on the dispersion coefficients was investigated. The results from the core flooding process indicated that the dispersion coefficient decreases with increasing salinity, hence the higher the density of the immobile phase (connate water) the lower the dispersion of CO2 into CH4. This is a significant finding given that the inclusion of the connate water and its salinity have an effect on the mixing of the gases in the core sample and should be given importance and included during simulation studies for field scale applications of Enhanced Gas Recovery (EGR). This is the first experimental investigation into the relationship between the connate water salinity and the dispersion coefficient in consolidated porous media. Keywords: Enhanced Gas Recovery; Dispersion Coefficient; Connate water Salinity; CO2 sequestratio

Building a Cognitive Dissonance Scale and Estimating Its Psychometric Characteristics among Umm Al-Qura University Female Students

This study aimed at building a cognitive dissonance scale that measures the dissonance and disharmony between believes, attitudes and values. The items of the measurement were articulated to suit the research female sample. Seven factors of the cognitive dissonance were extracted through the factor analysis of the answers of the sample which consists of 1097 female students from Umm Al-Qura University. Then, the factors were named according to the items they contain as follows: The family dimension, the emotional dimension, self-compatibility dimension, control and dominance dimension, social dimension, educational dimension and discipline and behavioral commitment dimension. Factorial validity and internal consistency estimates wer acceptable. The results of the study generally show the possibility of extracting cognitive dissonance. They also show that the current scale of cognitive dissonance is valid and meets the required standard specifications. Therefore it can be used in other studies. It is also recommended that more tests be made on the results, particularly on other samples in the future