تدريب Shadowing: Air Conditioning System Basics hvacr how does it work - تعلم التحدث بالإنجليزية عبر الفيديو
جارٍ إنشاء الدرس...
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sponsored by danfoss when we look at a typical refrigeration system we have the compressor
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the condenser the expansion valve and the evaporator the condenser
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and the evaporator are both heat exchangers the condenser sits outside the property
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and the evaporator sits inside the room being cooled the compressor circulates a refrigerant in the pipe work
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which cycles between all of these components the expansion valve regulates
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the flow of refrigerant the refrigerant is a specially designed fluid
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which can change between being a liquid and a gas very easily and that's
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because it has a very low boiling point for example refrigerant
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are for 10 a will boil at negative 48 degrees Celsius
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or negative 55 degrees Fahrenheit although this will change with pressure
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but if the refrigerant is inside a pipe within a room
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and the room is at 30 degrees Celsius
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or 86 degrees Fahrenheit then this will be more than enough to cause it to boil from a liquid into a vapor.
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By the way if you want some refrigerant charts you can download these for free from our website.
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I'll link to these in the video description down below.
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So the The refrigerant is entering the evaporator as a low pressure, low temperature liquid vapor mixture.
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It flows on the inside of the pipe
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and at the same time a fan is moving the ambient air of the room over the outside of the pipe.
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This causes the refrigerant to boil.
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It will absorb the heat from the air through the pipe wall and then it evaporates.
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As the refrigerant evaporates, it carries away the heat.
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It's similar to when we boiled water.
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The water heats up, it evaporates and turns into steam and carries this heat away.
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So the air on the outside is entering hot and it's leaving cold.
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The refrigerant continues to travel through the evaporator, picking up more heat which boils it further until it becomes slightly superheated.
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This basically means it's now completely gas and doesn't contain any droplets of liquid refrigerant.
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Liquid damages the compressor, so we want to ensure it can't reach the compressor.
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The compressor sucks in the refrigerant, which is leaving the evaporator as a low -pressure, low -temperature, slightly superheated vapour.
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It then squeezes this together into a much smaller space, and so the pressure increases.
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All the heat which was picked up in the evaporator is now contained in a much smaller volume, so the temperature will increase.
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This is very important and we will see why in just a moment.
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But if you've ever pumped up a bicycle tyre, you will notice the pump becomes hotter as it's compressing the air.
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The refrigerant is then pushed into the condenser where it enters as a high -pressure, high -temperature, superheated vapour.
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the condenser is located outside
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and the outside air might be very warm on a summer's
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day as heat always flows from hot to cold we need to ensure
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that the refrigerant is hotter than the outside air otherwise the
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unwanted heat will not be able to leave the refrigerant and leave our system
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a fan will help to blow ambient air over the condenser to remove this heat
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so the outside air is entering warm picking up heat
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and leaving hot as the heat is removed by the air
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this causes the refrigerant to condense back into a liquid it's a little bit like
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when steam hits the window on a cold day the window is cold
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so it condenses the steam from a vapor into a liquid
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and then this liquid starts to run down the window the
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refrigerant therefore exits as a high pressure medium temperature saturated liquid
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and this heads to the expansion valve the expansion valve needs
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to regulate the amount of refrigerant entering the evaporator to control the superheat
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if it allows too much refrigerant to flow it can flood the evaporator
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so the refrigerant doesn't evaporate a liquid reaches the compressor
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and possibly destroys it but
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if it lets in too little refrigerant the system won't provide enough cooling and
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so it operates inefficiently the expansion valve regulates the refrigerant by
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only allowing it to pass through a small hole this creates
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a large pressure difference across the valve one side is the high -pressure liquid the other side is almost empty
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The small hole causes it to almost spray into the evaporator as a part liquid, part vapor mixture.
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The refrigerant will expand to try and fill the empty space on the other side
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and this will cause it to drop in pressure as well as temperature.
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It's a little bit like spraying a deodorant can or a spray paint can.
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It flows through a small hole causing it to expand as a part vapor
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and part liquid mixture
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and then we can feel the can become cooler now the
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original method to control this was by using a fixed orifice device
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and you might still find these on the back of your
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refrigerators the hole within this device was a fixed size
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so the entire system would simply turn on
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and off to meet the cooling demand it does work
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but we can't maintain a stable temperature control
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because the system is simply turning on
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and off the next evolution was the thermostatic expansion valve this is still widely used today
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and it senses the superheat at the outlet through a bulb
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which is filled with another refrigerant this other refrigerant will expand to close the valve
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when the superheat is too high and it condenses to open the valve when the superheat is too low.
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This type of valve needs to be manually calculated and adjusted by a technician.
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It does work very well but it's prone to mistakes.
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It also takes a long time to calculate and set up
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and it is also only adjusted once per service visit which is not ideal.
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It will also not allow peak performance.
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However it does work very well and these will continue to be used for many years.
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And And so the latest evolution is to use electronic expansion valves.
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These use a controller to measure the exact temperature and pressure
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and adjust the valve position automatically in real time to ensure optimal performance and maximum system efficiency.
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Okay that's it for this video but to continue learning about HVAC
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and refrigeration engineering click on one of the videos on screen now and I'll catch you there for the next lesson.
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Don't forget to follow us on Facebook, Twitter, LinkedIn, Instagram as well as theengineeringmindset .com
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المفردات وملاحظات التحدث لهذا الدرس
هذا الدرس في المحادثة مبني على الفيديو “Air Conditioning System Basics hvacr how does it work”. أكثر الكلمات تكرارًا في الفيديو: refrigerant, liquid, valve, heat, evaporator. يحتوي هذا الفيديو على 85 جملة و1097 كلمة للتدرب على الترديد. مدة الكلام 7:15. يتكلم المتحدث بسرعة طبيعية، نحو 151 كلمة في الدقيقة، قريبة من المحادثة اليومية. 77% فقط من الكلمات ضمن أكثر 3,000 كلمة شيوعًا في الإنجليزية، فالمفردات صعبة نسبيًا.
أهم المفردات في هذا الفيديو
15 كلمة من الفيديو تستحق التعلّم، مع النطق والمعنى:
| الكلمة | النطق | المعنى |
|---|---|---|
| liquid اسم | /ˈlɪk.wɪd/ | سَائِل, مَائِع |
| valve اسم | /ˈvælv/ | صِمَام |
| boil فعل | /bɔɪ(ə)l/ | غَلَى |
| pipe اسم | /ˈpaɪp/ | مِزْمَار |
| vapor اسم | /ˈveɪpɚ/ | بُخَار |
| expand فعل | /ɪkˈspænd/ | وَسَّعَ |
| mixture اسم | /ˈmɪkst͡ʃɚ/ | خَلِيط |
| regulate فعل | /ˈɹɛɡ.jə.leɪt/ | ضَبَطَ |
| evolution اسم | /ˌiːvəˈluːʃ(ə)n/ | تَطَوُّر |
| pump اسم | /pʌmp/ | مِضَخَّة |
| calculate فعل | /ˈkælkjʊleɪt/ | حَسَبَ |
| stable اسم | /ˈsteɪ.bəl/ | حَظِيرَة, اِسْطَبْل |
| chart اسم | /t͡ʃɑɹt/ | مُخَطَّط بَيَانِيّ, مُخَطَط |
| lesson اسم | /ˈlɛs.ən/ | دَرْس, حِصَّة |
| ideal صفة | /aɪˈdi(ə)l/ | مِثَالِيّ |
الأفعال المركبة التي ستسمعها
| الكلمة | المعنى |
|---|---|
| pick up فعل | قَطَفَ |
| heat up فعل | سَخَّنَ |
| pass through فعل | اِخْتَرَقَ, نَفَذَ |
القواعد في هذا الفيديو
أكثر التراكيب التي يستخدمها المتحدث، مع العبارات نفسها من الفيديو:
| التركيب | في الفيديو |
|---|---|
| المبني للمجهول be + اسم المفعول — التركيز على ما يحدث لا على من يفعله | being cooled · was picked · is located |
| جمل الوصل who / which + جملة — معلومة إضافية عن شخص أو شيء | refrigerant, which is · heat which was · visit which is |
نطق يحتاج إلى انتباه
يستخدم المتحدث 9 من الصيغ المختصرة، مثل can't, doesn't, I'll. انطقها بصيغتها القصيرة كما تسمعها.
- أصوات “sh” و“zh”: evolution /ˌiːvəˈluːʃ(ə)n/, efficiency /ɪˈfɪʃ.ən.si/, specially /ˈspɛʃəli/, technician /tɛkˈnɪʃən/
- الكلمات الطويلة — انتبه لموضع النبر: evolution /ˌiːvəˈluːʃ(ə)n/, efficiency /ɪˈfɪʃ.ən.si/, manually /ˈmænj(u)əliː/, refrigerator /ɹɪˈfɹɪd͡ʒ.əˌɹeɪ.tɚ/, evaporator /ɪˈvæp.ə.ɹeɪt.ɚ/
أصوات يجدها متحدثو العربية صعبة:
- /p/ — ليس /b/: انطقه مع نفخة هواء: pipe /ˈpaɪp/, vapor /ˈveɪpɚ/, expand /ɪkˈspænd/, spray /spɹeɪ/, pump /pʌmp/
- /v/ — ليس /f/: مع اهتزاز الأوتار الصوتية: valve /ˈvælv/, vapor /ˈveɪpɚ/, evolution /ˌiːvəˈluːʃ(ə)n/, evaporator /ɪˈvæp.ə.ɹeɪt.ɚ/, evaporate /ɪˈvæp.ə.ɹeɪt/
- تتابع الصوامت — لا تضف حركة بينها: valve /ˈvælv/, expand /ɪkˈspænd/, mixture /ˈmɪkst͡ʃɚ/, spray /spɹeɪ/, adjust /əˈd͡ʒʌst/
كيف تتدرب بهذا الفيديو
- استمع إلى الفيديو كاملًا مرة واحدة دون أن تتكلم، ودوّن الكلمات التي لا تعرفها.
- ابدأ بسرعة 0.75×، وردّد جملة جملة، ثم عُد إلى السرعة العادية عندما يصبح الأمر سهلًا.
- سجّل صوتك وقارنه بالأصل، مع الانتباه إلى كلمات مثل liquid, valve, boil.
ما هي تقنية التظليل الصوتي؟
التظليل الصوتي (Shadowing) تقنية تعلم لغة مدعومة علمياً، طُورت أصلاً لتدريب المترجمين الفوريين المحترفين. الطريقة بسيطة لكنها قوية: تستمع لصوت إنجليزي أصلي وتكرره فوراً بصوت عالٍ — كظل يتبع المتحدث بتأخير 1-2 ثانية. تُظهر الأبحاث تحسناً كبيراً في دقة النطق والتنغيم والإيقاع وربط الأصوات والاستماع والطلاقة.