یہ وطن تمھارا ہے تم ہو پاسبان اس کے
نحمدہ ونصلی علی رسولہ الکریم امّا بعد فاعوذ بااللہ من الشیطن الرجیم
بسم اللہ الرحمن الرحیم
معزز اسا تذہ کرام اور میرے ہم مکتب ساتھیو!
آج مجھے جس عنوان پرلب کشائی کی سعادت حاصل ہورہی ہے وہ ہے:’’یہ وطن تمہارا ہے تم ہو پاسبان اس کے ‘‘
صاحبِ صدر!
جو چیز اپنی ملکیت ہوتی ہے، جس چیز کے ہم مالک ہوتے ہیں۔ اس کی پاسبانی ، اس کی نگہبانی ، اس کی حفاظت بھی ہماری ذمہ داری ہوتی ہے، ہم مال واسباب اور سیم وزر کے مالک ہیں تو ان کی حفاظت بھی ہم نے ہی کرنی ہے۔
صدرِزی وقار!
یہ ہمارا وطن ہمیں جان سے بھی زیادہ عزیز ہے، ہمیں اس کے ریگستانوں سے محبت ہے، ہمیں اس کے بیابانوں سے انس ہے، ہمیں اس کے کوہستانوں سے پیار ہے ، ہمیں اس کے گلستانوں اور بوستانوں سے عقیدت ہے، ہمیں اس کے حیوانوں اور انسانوں سے محبت ہے۔
جنابِ صدر!
اس کی فضاؤں کی سرسراہٹ ، اس کی ہواؤں کی آہٹ ، اس کی آبشاروں کی گڑگڑاہٹ ، اس کے بادلوں کی گھن گرج، اس کی بادِ نسیم کی اٹھکیلیاں ، اس کی کہکشا ئوں کے چلتے ہوئے رنگ، اس کے قمر کے روشن نظارے، اس کے آفتاب کے حسین چمکارے، یہ سب مجھے حیات نو بخشتے ہیں، اس لیے کہ یہ سب میرے اپنے ہیں۔
موج بڑھے یا آندھی آئے دیا جلائے رکھنا ہے
گھر کی خاطر سب دکھ جھیلیں گھر تو آخر اپنا ہے
معزز سامعین!
اس کے دامن میں پھیلی ہوئی ندیوں کی نغمہ خوانی ، اس کے میدانوں کو گھیرے ہوئے گھنے جنگلات کی فراوانی، اس کی فضاؤں میں محو پرواز طائران خوش الحان ، اس کی ہواؤں میں ہوا بازوں کی قلابازیاں ، اس کے گلستان میں...
Since from the beginning of humanity means of communication have always been an essential need for mankind. To convey the message and to find means to communicate and express one’s thought one needs a mean to transmit the information to others. That is called communication. With the passage of time and advancement communication means also took modern shape and became advance. Islam as a complete code of life, guides humanity in the all fields of sociology, economic, politics, including mass communication. Allah the Almighty sent messengers and Prophets for the guidance of people. So they served the humanity in different periods of time in different areas. Ḥaẓrat Muḥammad (ﷺ) the last prophet of Allah used these means of communication for the prevalence and preaching of Islam, and left behind a remarkable legacy in the field of mass communication for the guidance till dooms day. Where there have been great changes in other fields and professions of life in the advanced world of contemporary era there had become a revolutionary change in the field of media. News all over the world spread in seconds. Media which is the strongest tool to approach people, but sorry to say that it is detracted badly by prevailing wrong values, vulgarity, jealousy and selfishness. There is a dire need to change the direction of noble that so (صلى الله عليه وسلم) Muhammad Prophet of methodology the towards media values like piousness, self-sacrifices, brotherhood and cooperation should be developed in people and for this purpose youth can play a pivotal and effective role in the field of mass communication. Eyes are looking towards youth of contemporary era to step forward by following our Holy contemporary the how that attempt humble a is article This. (صلى الله عليه وسلم) Prophet youth can play its role by using means of communication by taking guidance from Prophetic Era to lead media towards right direction.
Shell and tube heat exchangers are widely used for various industrial refrigeration applications. There is no data available in open literature on the direct expansion evaporation characteristics of refrigerants on the shell side of tube bundle. With the current Ozone Depletion and Global Warming issues it is critical to develop systems with low charge refrigerants especially with natural refrigerants such as ammonia which has zero Ozone Depletion Potential (ODP) and zero Global Warming Potential (GWP). A comprehensive literature survey has been presented to summarize previous single phase correlations for estimating heat transfer coefficient inside circular tubes and studies performed with ammonia boiling outside single tube and bundles and the correlations thereof developed. Considerable amount of work has been performed and correlations developed for estimating heat transfer and pressure drop in smooth circular tubes for single phase flow. There are limited studies available on pool boiling and spray evaporation of ammonia outside single tube and bundle. As of now, there are no studies available in the open literature on the subject of direct expansion evaporation of refrigerants. The basic purpose of the present study is to quantify the effects of various parameters such as saturation temperature, heat flux, inlet quality and degree of exit superheat on the heat transfer performance for ammonia boiling on the shell side of tube bundle under direct expansion mode, and to develop empirical correlations. Overall performance of the heat exchanger and performance of individual passes are also studied. The design and details of the single phase and two phase experimental setup, instrumentations, data acquisition system and test heat exchanger are described. Single phase experiments were performed to develop single phase correlations for specific geometry and flow conditions for estimating heat transfer coefficient inside tube bundle using simple Wilson plot and modified Wilson plot method. Prandtl number was varied from 10 to 20, with Reynolds number ranging from 3000 to 15000. The correlations developed are compared vii with existing single phase correlations and were found to be in good agreement with the previous studies. Two phase experiments were performed at steady state conditions with ammonia boiling on the shell side of heat exchanger, while water/glycol solution flowing in the tubes. Saturation temperature was varied from -1.7 to -20 , inlet quality was varied from 0 to 0.3, and heat flux was varied between 5 and 45 , with exit degree of superheat ranging from 2 to 10 . Heat transfer coefficient was observed to increase with saturation temperature and heat flux and decrease with exit superheat (quality) because of the diminishing effect of boiling and dominance of single-phase sensible regime. The effects of inlet quality on the average bundle performance were found to be negligible. Heat transfer coefficient slightly decreased or remained unchanged with inlet quality. The quality effects were found to be more dominant at higher saturation temperature than at lower saturation temperature. Bundle effect was observed between the passes which was a function of saturation temperature, heat flux and exit degree superheat. The present data suggests that bundle effect is less significant at low heat flux, with lower degree of exit superheat. The variations in heat transfer coefficients of individual passes are usually smaller under these circumstances. At higher exit degree superheat and heat flux the upper tubes experienced greater dry out which resulted in a sharp drop in their performance. The trend was similar across the saturation temperature range. The effects of exit degree of superheat became more dominant on the bundle performance over heat flux when ammonia was subjected to vapor quality at the inlet of the evaporator. With increase in the inlet quality the performance of lower three passes converge. Two phase pressure drop under direct expansion mode was found to be sufficiently small. The effects of saturation temperature and inlet quality on pressure drop were negligible. Pressure drop marginally increased with decrease in the degree of exit superheat and with increase in the heat flux.