什么是制冷剂混合的“中间点”?——伟德备用空调的学校

通过 2018年6月13日

什么是制冷剂混合的“中间点”?

正如我们在之前的几篇文章中所提到的(比如这个)，许多混合制冷剂都有滑移，这意味着它们在一定的温度范围内沸腾和凝结，而不是在一个温度范围内。

以R407c制冷剂为例。这是一种共沸混合物，这意味着如果你不考虑它的话，它有足够的滑脱力，会有很大的不同。

例如，在运行R407c的蒸发器线圈上，离开TXV的制冷剂将在气泡点开始沸腾。假设蒸发器中的压力是80 PSIG;气泡温度为40°。

随着制冷剂继续沸腾，温度将向露点(50.8°)升高。在R407c系统上，任何温度在80psig下上升到50.8°以上都是过热，这意味着制冷剂100%是蒸汽。

因此，我们计算过热度为露点以上的温度，过冷为气泡点以下的温度。冷凝温度和蒸发器温度不是固定的，但它们在气泡和露水之间滑翔，并在制冷剂状态变化时返回。

但是，当计算目标压头(冷凝压力)和吸气压力(蒸发器压力)，也称为蒸发器TD和冷凝温度超过周围环境时，这对蒸发器和冷凝温度意味着什么?

最简单的方法是使用露点和冒泡点之间的中点来计算CTOA和DTD。

在上面的例子中，你可以简单地计算50.8°+ 40°= 90.8 | 90.8÷2＝45.5°蒸发器平均温度或中点

爱默生指出用40%的气泡和60%的露珠来计算蒸发器会更好，但额外的复杂性通常不足以说明问题。

我做这个视频是为了进一步说明:

布莱恩

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The CS compressors are hermetic reciprocating compressors that can work with some of the newer refrigerants. You will likely see these compressors in applications with smaller tonnages.\u00a0<\/p>\n

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You\u2019ll usually want to charge these compressors with liquid refrigerant. If you have more than 6 pounds of charge in the system, using an accumulator is recommended. Under those charge conditions, the system also needs a check valve between the receiver and the condenser.<\/p>\n

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Suction line pressure drop is one of the most important things to pay attention to in the system. Make sure the suction line is of an appropriate size, that filter-driers don\u2019t have restrictions, and that accumulators aren\u2019t clogged. Overall, many manufacturers recommend removing the duction driers to keep the pressure drop minimal.<\/p>\n

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The recommended runtime for these compressors is also very short, only 5 minutes. CS compressors should cycle no more than 12 times per hour, and the off-time between cycles should be a minimum of 10 seconds.<\/p>\n

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Before returning or replacing a compressor, make sure you check all of the electrical components, including the capacitor. If the compressor hums but has power, you could simply have a capacitor or potential relay issue.<\/p>\n

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Trevor and Bryan also discuss:<\/p>\n

Return gas temperatures<\/li>\n

Discharge line temperature<\/li>\n

Compressor superheat and flooded conditions with refrigerant blends<\/li>\n

Crankcase heaters<\/li>\n

Pump-down recommendations to stop short cycling<\/li>\n

Initial charge vs. recharge<\/li>\n

Metering devices<\/li>\n

Line sizing<\/li>\n

Electrical shorts<\/li>\n

Sticking relays<\/li>\n

Single-phase vs. three-phase power<\/li>\n

Megohm testing<\/li>\n

Purging with and flowing nitrogen<\/li>\n

Burnout cleanup procedures<\/li>\n

Locking\/tagging out equipment<\/li>\n

Hard start kits, potential relays, and start capacitors<\/li>\n<\/ul>\n
If you have an iPhone, subscribe to the podcast HERE<\/a>, and if you have an Android phone, subscribe HERE<\/a>.<\/p>\n
\u00a0<\/p>\n
Check out our handy calculators HERE<\/a>.<\/p>\n
Check out information on the 2022 HVACR Training Symposium at \/\/www.desamelle.com\/symposium\/<\/a>.<\/p>\n","author":"Bryan Orr","date":"10\/28\/2021","link":"https:\/\/traffic.libsyn.com\/secure\/hvacschool\/Copeland_Reciprocating_CS_Compressors_w_Trevor.mp3","src":"https:\/\/traffic.libsyn.com\/secure\/hvacschool\/Copeland_Reciprocating_CS_Compressors_w_Trevor.mp3?dest-id=425611","featured":"\/\/www.desamelle.com\/wp-content\/uploads\/2021\/10\/Copeland_Reciprocating_CS_Compressors_w_Trevor-768x768.jpg","mediatype":"audio","featured_id":76128,"key":"eec529e0f8169c83e00c6d0058ecac38","fset":"\/\/www.desamelle.com\/wp-content\/uploads\/2021\/10\/Copeland_Reciprocating_CS_Compressors_w_Trevor-768x768.jpg 768w, \/\/www.desamelle.com\/wp-content\/uploads\/2021\/10\/Copeland_Reciprocating_CS_Compressors_w_Trevor-300x300.jpg 300w, \/\/www.desamelle.com\/wp-content\/uploads\/2021\/10\/Copeland_Reciprocating_CS_Compressors_w_Trevor-1024x1024.jpg 1024w, \/\/www.desamelle.com\/wp-content\/uploads\/2021\/10\/Copeland_Reciprocating_CS_Compressors_w_Trevor-150x150.jpg 150w, \/\/www.desamelle.com\/wp-content\/uploads\/2021\/10\/Copeland_Reciprocating_CS_Compressors_w_Trevor-1536x1536.jpg 1536w, \/\/www.desamelle.com\/wp-content\/uploads\/2021\/10\/Copeland_Reciprocating_CS_Compressors_w_Trevor-2048x2048.jpg 2048w"},"ppe-506-2":{"title":"Adiabatic Cooling – Short 130","description":"
In this short podcast episode, Bryan explains the science behind adiabatic cooling. Adiabatic cooling occurs in specific HVAC\/R applications and in our environment as air temperatures and pressures change.<\/p>\n
\u00a0<\/p>\n
When we think of cooling, we refer to the loss of heat; we are either referring to the change in the total BTU content of the air mass or the temperature change. Adiabatic cooling takes sensible heat and transforms it into latent heat.<\/p>\n
\u00a0<\/p>\n
The most simple forms of adiabatic cooling can be seen in cooling towers and swamp coolers. In evaporative or swamp coolers, you have a pad saturated with water, and air moves over it. When air moves over the media, some of the energy helps evaporate the moisture on the pads, so the air loses sensible heat and becomes cooler. The thermal enthalpy (total heat content) stays the same, but some of the sensible heat has transferred to latent heat.\u00a0<\/p>\n
\u00a0<\/p>\n
Air that goes through a swamp cooler goes in with higher temperature and lower humidity, and it leaves with a lower temperature and higher humidity. The BTU content stays the same; the energy merely transforms. As a result, we usually only use swamp coolers in arid environments where higher humidity is desirable. You also can\u2019t compare these to compression-refrigeration systems because compression refrigeration aims to change the BTU content and is NOT adiabatic.<\/p>\n
\u00a0<\/p>\n
When we run air over an evaporator coil, some of the water vapor in the air condenses to liquid water in the drain pan. Some of the energy in the refrigerant changes the state of the water vapor to liquid water instead of changing the temperature. You\u2019ll see a lower delta T when your return relative humidity (RH) is higher.<\/p>\n
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If you have an iPhone, subscribe to the podcast HERE<\/a>, and if you have an Android phone, subscribe HERE<\/a>.<\/p>\n
\u00a0<\/p>\n
Check out our handy calculators HERE<\/a>.<\/p>\n
Check out information on the 2022 HVACR Training Symposium at \/\/www.desamelle.com\/symposium\/<\/a>.<\/p>\n","author":"Bryan Orr","date":"10\/26\/2021","link":"https:\/\/traffic.libsyn.com\/secure\/hvacschool\/Adiabatic_Cooling_-_Short_130.mp3","src":"https:\/\/traffic.libsyn.com\/secure\/hvacschool\/Adiabatic_Cooling_-_Short_130.mp3?dest-id=425611","featured":"\/\/www.desamelle.com\/wp-content\/uploads\/2021\/10\/Adiabatic_Cooling_-_Short_130-768x768.jpg","mediatype":"audio","featured_id":76082,"key":"ce364255c9ebb052a43ce1cd35872681","fset":"\/\/www.desamelle.com\/wp-content\/uploads\/2021\/10\/Adiabatic_Cooling_-_Short_130-768x768.jpg 768w, \/\/www.desamelle.com\/wp-content\/uploads\/2021\/10\/Adiabatic_Cooling_-_Short_130-300x300.jpg 300w, \/\/www.desamelle.com\/wp-content\/uploads\/2021\/10\/Adiabatic_Cooling_-_Short_130-1024x1024.jpg 1024w, \/\/www.desamelle.com\/wp-content\/uploads\/2021\/10\/Adiabatic_Cooling_-_Short_130-150x150.jpg 150w, \/\/www.desamelle.com\/wp-content\/uploads\/2021\/10\/Adiabatic_Cooling_-_Short_130-1536x1536.jpg 1536w, \/\/www.desamelle.com\/wp-content\/uploads\/2021\/10\/Adiabatic_Cooling_-_Short_130-2048x2048.jpg 2048w"},"ppe-506-3":{"title":"Fighting Boredom at Work – Short 129","description":"
In this short podcast episode, Bryan shares his top tips for fighting boredom at work. You can use these tips to help you get out of a rut if you don\u2019t feel productive or get bored easily.<\/p>\n
\u00a0<\/p>\n
The first tip is to see the art or creativity in your work. Even in the HVAC industry, there are plenty of opportunities for artisan skills and craftsmanship. When you see your work as an art that you need to refine, especially in terms of duct strapping and brazing, it\u2019s easier to get engaged in your work and feel proud of it.<\/p>\n
\u00a0<\/p>\n
Another way to stop from getting bored is to do more things that challenge you. Being constantly challenged and being out of your comfort zone keeps you interested and can even spark a new passion.<\/p>\n
\u00a0<\/p>\n
Pursuing mastery allows you to focus on one particular skill or subject to become an expert. When you master a skill, you also become a marketable job candidate and can carve out a niche within your organization. Mastery is about going deep rather than wide, and more people will feel enriched by working towards mastery than others.<\/p>\n
\u00a0<\/p>\n
If you\u2019re a social person, finding a community can keep you from getting bored. When you have a community, you will be around people who have the same interests and experience the same challenges as you. So, you won\u2019t get bored from feeling alone.<\/p>\n
\u00a0<\/p>\n
Mentorship is another way to rekindle your passion. When you choose to invest in and guide less experienced people in the trade, you can feel a renewed sense of purpose in your work.\u00a0<\/p>\n
\u00a0<\/p>\n
And if you\u2019re REALLY bored, you can change everything up entirely and try something new.<\/p>\n
\u00a0<\/p>\n
If you have an iPhone, subscribe to the podcast HERE<\/a>, and if you have an Android phone, subscribe HERE<\/a>.<\/p>\n
\u00a0<\/p>\n
Check out our handy calculators HERE<\/a>.<\/p>\n
Check out information on the 2022 HVACR Training Symposium at \/\/www.desamelle.com\/symposium\/<\/a>.<\/p>\n","author":"Bryan Orr","date":"10\/19\/2021","link":"https:\/\/traffic.libsyn.com\/secure\/hvacschool\/Fighting_Boredom_at_Work_-_Short_129.mp3","src":"https:\/\/traffic.libsyn.com\/secure\/hvacschool\/Fighting_Boredom_at_Work_-_Short_129.mp3?dest-id=425611","featured":"\/\/www.desamelle.com\/wp-content\/uploads\/2021\/10\/Fighting_Boredom_at_Work_-_Short_129-768x768.jpg","mediatype":"audio","featured_id":75915,"key":"23320b86d146c620dbcb1f8cb6707db1","fset":"\/\/www.desamelle.com\/wp-content\/uploads\/2021\/10\/Fighting_Boredom_at_Work_-_Short_129-768x768.jpg 768w, \/\/www.desamelle.com\/wp-content\/uploads\/2021\/10\/Fighting_Boredom_at_Work_-_Short_129-300x300.jpg 300w, \/\/www.desamelle.com\/wp-content\/uploads\/2021\/10\/Fighting_Boredom_at_Work_-_Short_129-1024x1024.jpg 1024w, \/\/www.desamelle.com\/wp-content\/uploads\/2021\/10\/Fighting_Boredom_at_Work_-_Short_129-150x150.jpg 150w, \/\/www.desamelle.com\/wp-content\/uploads\/2021\/10\/Fighting_Boredom_at_Work_-_Short_129-1536x1536.jpg 1536w, \/\/www.desamelle.com\/wp-content\/uploads\/2021\/10\/Fighting_Boredom_at_Work_-_Short_129-2048x2048.jpg 2048w"},"ppe-506-4":{"title":"Review Of Vacuum For Service Revisted","description":"
In this podcast episode, Bryan goes through the addendum to the book Review of Vacuum for Service Engineers<\/em>. He and Jim Bergmann had the honor of revising the latest edition in 2020. You can get the latest edition of Review of Vacuum for Service Engineers<\/em> from TruTech Tools HERE<\/a>.<\/p>\n
\u00a0<\/p>\n
Pulling a Schrader core before evacuation makes a big difference in the speed of the evacuation. You can use a core remover tool to pull the cores when the system is NOT pressurized.\u00a0<\/p>\n
\u00a0<\/p>\n
There are three common types of ports to access the system: the Schrader core, high-flow core (CoreMax), and the multi-position service valve. You can mid-seat the multi-position service valve for high flow, but you need to remove or depress cores on the other two port types. (You must use a special CoreMax CRT to remove high-flow cores.)<\/p>\n
\u00a0<\/p>\n
Three factors limit the speed of evacuation: the conductance speed of the pump, of the connecting hoses, and of the system. The hoses and manifold can severely impact evacuation. TXV and piston metering devices have short orifices and have very little impact on the evacuation time; on TXVs and EXVs, the valve should be fully open.<\/p>\n
\u00a0<\/p>\n
When pulling a vacuum, make sure the vacuum pump works properly and has clean oil. Once you know that the pump is working, only pull on a tight system (no leaks) and make sure the seals are in good shape.\u00a0\u00a0<\/p>\n
\u00a0<\/p>\n
Bryan also discusses:<\/p>\n

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“什么是制冷剂混合的“中点”?”

帕特里克•德怀尔 说:

2021.10.30在22:34

谢谢。

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戴夫说:

2021.10.30在23:59

¡谢谢caballero !我不得不把它放到我的youtube观看列表上，并且在另一个时间刷新。

喜欢侧边栏动作显示的手机应用程序的特写!!

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马特说:

2021.10.30在十七36

我用SuperDew和SubBubble来帮助我记忆

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