中文用户可以浏览：无油涡旋压缩机国内外研究现状

Scroll compress another efficient positive displacement compressor after reciprocating compressors, rotor compressor and screw compressor. It’s know as the most advanced continuous compressor. This kind of compressor are known for operating more efficiently and quietly than conventional compressors. Compared to pistons, its main component is only 10% of the former, the volume reduced about 40%, efficiency improved 10%, weight is only 85% of the former.

With the development of industry, clean air is needed in some particular field. At this time, oil free compressor become the major option. Because of the advantages of oil free scroll compressor, it becomes the focus in the resarch of compressor.

Oil free compressor was founded between 1920s and 1930s. Sulzer Brothers Ltd., from Swiss, first patented Labyrinth seal oil lubrication compressor. At the beginning of 1950s, first oil free compressor appeared on the market. Shenyang air compressor factory and Lanzhou Institute of Chemical Physics, CAS, are the two institutions which engaged in researching oil free compressor first in China.

The oil free compressor has very favorable prospect of development. The first factory, which produce oil free compressor , in China, estimated to make about 5 billion in after 2011 when it go into full operation.

However, research on oil free scroll compressor is still fairly few. It faces many shortages. How to seal and lubricate remains the big challenges in improving its efficient. Compared to compressors work with lubricant oil, the leakage is much bigger.

In order to lubricate without oil, we need to inlay self-lubricatingmaterial. The most popular self-lubricatingmaterial are PTFE, PEEK, PESF and PES.

The old experience and the traditional method of 2-D design remains the major methods for design and manufacture. But these two methods have the same shortage of inefficiency and long development cycle. So it can not meet the needs now. To find a new method becomes important.

中文用户可以查看中文版：无油润滑涡旋压缩机设计计算步骤

Disclaimer:

This calculation method is suit for designing a compressor that you know the compressor displacement Q_d (V³/min) and suction pressure p_s as well as the exhaust pressure p_d (MPa). And according to a Chinese paper “Choice of Bask Geometric Parameters and Structure Parameter,λ=h/Pt , on a Scroll Compressor” by Gu Zhaolin, published on “Compressor Technology”, 1996, we choose Pt、t and h as bask geometric parameters. So I modified the calculate steps to this method:

1. Calculate the indicated power of electromotor. P_i (Kw)

equation for calculating the indicated power of electromotor

You can find this equation in document [2] at page 62. In this book, it use  kgf/cm² as unit of pressure. So I made a small change in order to change the pressure unit to IU MPa.

2. Compute motor power P_e (Kw)

The leakage and friction factors concerned, shaft power Pz can be counted through this equation:

P_z=1.12P_e

Make sure there are about 5%～15% power reserve, the motor power Pe should be:

P_e=(1.05～1.15)P_z

3. Select motor speed n_w, it should be between 1000 and 4000r/min

4. Calculate the exhaust volume V_d (m³/r)

V_d=Q_d/(i*nw)

‘i’ in this equation is a parameter defined by the amount of compression chamber. If there is just one orbiting scroll and one fixed scroll, i should be 2. For compressor with Z orbiting scrolls and fixed scrolls, i should be 2*Z.

5. Calculate the suction volume V_s (m³/r)

Use a ideal gas model to simplify the calculation and assume the cycle as adiabatic. So:

pV^k=C

k is the adiabatic exponent of working medium or refrigerant. The adiabatic exponent is 1.4. The suction volume can be defined:

equation for calculating the suction volume of scroll compressor

6. Geometric interior volume specific ratio ε_v

ε_v=V_s/V_d

7. Select  scroll pitch P_t(mm), scroll width t (mm). t should be 2～6mm

8. The angle that the involute beginning α (rad)

α=pi*t/P_t

pi=3.1415926535 897932

9. The maximum angle of involute Φ_e(rad) and the exhaust angle θ_d(rad)

ε_v=(2*Φ_e-3pi)/[2(Φ_e-θ_d)-3pi]

equation 1 for calculating the maximum angle of involute Φe and the exhaust angle θd

equation 2 for calculating the maximum angle of involute Φe and the exhaust angle θd

You will get the answer by combine the three equation. You may need tools like Matlab to get the  result. http://www.zhangpeng.info/

10. Scroll height h (mm)

V_s*1000000=P_t(P_t/2-t)h(2Φ_e-3pi)

You should adjust your parameters to use unit of ‘m’ other than ‘mm’. But I defined all the distance use the unit of ‘mm’, so I plus a 1000000 to make the change.

11. Check λ=h/P_t if it appropriate

Some paper said λ should between 1.5 and 2.5. If the λ you gained exceed the limit, duplicate step 7-11.

12. Radius of basic circle R_b (mm)

R_b=P_t/2pi

13. Radius of shaft circle R_or (mm)

R_or=(P_t-2t)/2

14. Balanced design of orbiting scroll.

15. Choose a oil-free format and the self-lubricatingmaterial

References:

1、刘振国.涡旋式流体机械与涡旋压缩机[M].机械工业出版社. 2009

2、编写组.活塞式压缩机设计[M].机械工业出版社. 1974

3、Gu Zhaolin, Yu Yongzhang. 涡旋压缩机设计计算研究[J].流体机械. 1996.2

4、Gu Zhaolin. Investigation of Scroll Compressor Design[J].低温工程. 1996.1

All these references are written in Chinese, you ask me if you have any question during reading these references.

中文用户请转移至：黑莓8830解锁方法及程序下载

I now want to share my experience on unlocking blackberry with peoples who want to use a locked blackberry. You should know, this free solution can not have effect on any model but some special models. As far as I know, MML can not unlock blcakberry 8820, 8900, 9500 and 9530. This unlocking progress can be splited into four steps. First is download softwares and install them into your computer. The second step is restoring blackberry. The third one is using MFI to unlock cell phone. Certainly, you need to install a new OS on your device.

1. Download softwares and intall them.

There are three applications you must use in unlocking a phone. They are BlackBerry Desktop Manager, .NET framework2.0 and MML. Some times, you may also need to download a few dll files.

Desktop Manager can be accesed at their official website. Go to download page here.

.NET Framework2.0 is a free soft by Microsft. Go to download page here.

I packed two MML files for you to choose:

A simplified edition for just 8100, 8110, 8120, 8200, 8300, 8310,8320, 8350, 8700, 8707, 8800, 8830 and 9530. Click here.

A complete MML file for most model. Click here.

Or you may need some dll files. Get them here.

If you find any problem in downloading files, contact me by leave a comment. I can send you one by email.

2. Restore blackberry

Use loader file to renew your phone to Factory OS. By click file name by specific model under HHFiles folder. For example, if you want to unlock a 8830, double click loader 8830.bat. You will continue with the third step when you see “No Application Linked” on the screen.

3. Unlock cell phone with MML

Please disconnect your network before you starting this step. You will see some error in runing MFI when you connet network. Follow this tips:

1. Copy all files to C: directory.

2. Open folder ‘bin’ and double click register.bat.

3. Double click bulding.bat

4. Run MML.exe

Uncheck Auto start.Click start and wait. About ten minutes later, you’ll see a big “1” on your phone screen and a “PASS” on MFI. When you see these, it’s to say, your blackberry is successfully unlocked.

4. Reinstall a OS

Do you still remember I suggest you download Desktop Manager? Use this to reinstall a new OS one your phone and all things get done.

Frequentlly appeared problems and solutions:

1. Cannot create CFP instance. Please ensure the BBCFPCOM driver is registered

You can download the simplified MML edition and run the buding.bat. Or you can do it yourself by input these code in Command Prompt Only:

regsvr32 c:\mml\bin\BBCFPCOM.dll
regsvr32 c:\mml\bin\GRSNVLibCOM.dll
regsvr32 c:\mml\bin\RIMRadioCOM.dll

2. NV library failed to load PRL file. Cannot find PRL-14672-001 on the server

Also I added all these files into the simplified MML edition.

3. Can not find ceutil.dll or rapi.dll in your system

Download them here. I packed the two dll files.

Make as whole theme

A theme contains much IDs. The id couldn’t appear twice protocol don’t allow it.  Make wp theme as a whole let you make less mistake.

Separate theme into models

This is a good way to let your theme have a great structure. For example, WP define a theme into Header, Siderbar, Footer and so on. And models can let you write codes more efficiency.

Optimize codes

Use less code. You can combine same CSS properties. For example, define a left tag like .left { float:left;} and use it when you need let a DIV float left.

Check compatibility

A site with error codes will never be trusted by users especially those webmasters. You may need to make your theme fit W3C standards. And make sure all data look correct.

SEO

Many wordpress users do not just write blog for themselves. So the may think of traffics when choosing a wp theme free. Put entry title front of blog title. Your title looks in search engines should be this format: post title + blog title. Add meta tag. Add keywords and description in your header tag. The third tip is to think about how to use <H> tag.

There are two kinds of wordpress themes: free or not free. I do think most blogger wouldn’t pay much for a blog theme. You may find some free services at most time. So where to get some great wordpress templates?

There are three ways you can get a free template.www.zhangpeng.info

First, you can find some great free template at wordpress.org. Many wordpress fans submit their templates here for users to download for free and get some honor.

Second, you can search for some free template directories. There are many websites collect some great template that wordpress.org don’t shows.

Third, ask a friend who know how to create wordpress template for a free one. Or you can ask me a wordpress theme and just buy me a coca cola. I will be happy to help you.

1. A valid passport and the copy of its homepage

2. One photograph (3.5cm*4.5cm)

3. Apply form for visa to Russia ( must fill in all the blanks)

4. Invitation Letter given by Russian migration official

5. Invitation Letter by Russia college ( university) and its copy

6. The contract with your college (university) and its copy

7. A copy of your graduation certificate

8. A blank statement that can proof enough capacity to pay ( offer a certificate that can proof the family relationships if the account was opened by you parents)

9.Valid emdical certificate ( validity 3 months) and a AIDS inspection reports (if you will stay in Russia more than 90 days)

10. Notarized copy of agree certificate by parents if you were under 18 years old

Do remember to take all these things listed above when preparing to apply for a visa for Russia. Hope you receive your visa.

Each color, in these rings, stands a number. Here is a table show their relation:

There are also two special color stands for measurement error. Gold stands a measurement error about ±5％ and silvery for ±10％. Some times, other colors like brown or green can also show the measurement error when the printed on the last ring. Brown for ±1％ red for ±0.2％ and green ±0.5%. www.zhangpeng.info

There are two kinds of resistance: resistance with four rings and resistance with five rings. The rings stands for the similar meaning. The key to judge a resistance is to identify the sequence of each rings. There are two ways to judge the sequence. Judge by the space between rings or distinguish the color that shows  measurement error.

Judge by the distance between rings

There have a different space between rings. The last space is always longer than first step. You can carefully check your resistance.

Distinguish the color that shows  measurement error first

As I told you above, gold and silvery always show a measurement error. If a resistance have a ring with color gold or silvery, it’s useful to identify the list by its special color.

Examples

On a resistance, the color ring show more details besides only numbers.

For a resistance with four rings, the first two rings show you the number. The third one tell you how many zeros behind the number.

The only difference between resistance with five rings and four rings resistance is that there are three rings show the number in the former one.

Here I give you a simple example:

You had know red for 2, purple for seven and there is just one zero behind it. So the exact resistance is 270Ω.

Let’s go to the detail: (I dropped the head of my resume for avoid spam to my email account)

Education:

2006/9 –Present Central South University, Bachelor
Thermal energy and power engineering, GPA: 3.26

• Three third-class scholarship

• Excellent League member

• CET-6, NCRE 3, SYB (Start Your Business) certificate

Project experience:

2008/5–Present National experimental research project
Project ID：081053386, Master

•Came up with the idea, got ￥7000 as experiment funds

•Frequently read English documents for latest knowledge

•Published a thesis “Analysis for the Feasibility of Semiconductor Thermoelectric Generator Used in Industrial Surplus Heat Recovery”

Practical Experience:

2009/6—2009/7 Aluminum Group of China branch in Henan, Intern

•Known basic knowledge of manufactory

•Reviewed the principle of automatic control

2008/8—2008/9 Zhu zhou smelting plant, Intern

•Recognized facilities which used in automation.   www.zhangpeng.info

2008/9—2009/6 League Secretary

•Led activities related with the Communist Youth League

•Our class was negotiate nominated as “wusi outstanding Youth League branch”

2006/9—2007/6 Diplomacy Department, Students Union, minister

•Successfully earned four support funds

Self Identification：

•Good communication skill

•Willing to work with others

Othersnterests & Skills：

IT skills
•Advanced at AutoCAD

•Basic understand of Ansys

• Skillful MS Office

Interests

•Like playing basketball and once joined in basketball game hold by my college twice

•Usually listen to music, reading and watch films

• Indulge in web design and run personal weblog: http://www.zhangpeng.info

About a couple days ago, I noticed that my google PR increase from 2 to 3. It’s a exciting thing because this blog just had one friend link. I can’t believe that I can get a PR 3 by just one link.

As I said, this blog has small traffic and can’t match the PR. I decided to boost my traffic by some free resources. These tools should not cost me much time.  www.zhangpeng.info

I picked up Blogupp, a tool focus on increasing blog traffic. The reason why I choose it is simple. Blogupp don’t need much of my information but just my blog URL. It’s free and with no additional conditions. It give me a back rate of 10:9 as the website said.

To get your free blogupp tools, just go to http://www.blogupp.com/

Blogupp will automatically give you three kinds of widget, for which size are 150*350, 150*188 and 300*188. Just choose one suit your blog most. You can see a live demo at my homepage.

We first use the Euler method to get a y_n+1 in the Improved Euler method. Then we use another method to amend the y_n+1 to let it more similar to the real y_n+1.

We express this new Improved Euler method by these two formulas:

y_n+1 = y_n + hf (x_n , y_n )
y_n+1 = y_n + h*[f (x_n , y_n )+f (x_n+1 , y_n+1 )]/2

When use computer for calculation in some engineering field, you should show the relationship between ‘y’ and ‘x’. You need also give a ‘h’.

A example to use Improved Euler method for solving heat transfer problem:(Use Matlab)

Euler method used in heat transfer calculation

Question: As the figure shows. T_∞=1500℃，T_w=500 ℃, T₀=20℃, a thermocouple which diameter is 1mm exposed in the air. The surface coefficient of heat transfer h=200W(m²/K)，ε=0.2. Thermocouple oxidation will create energy at a rate of q=1000W/m³.  Determine the relation ship between temperature of thermocouple and time. [additional properties of thermocouple:ρ=8000kg/m³，c=0.38kJ/(kg*K)，λ=50W/(m*K)]

Answer: We use Improved Euler Question to solve this problem.  www.zhangpeng.info

The source code in Matlab here:

function [x,y]=eulerg(x,y,h,N)
x=zeros(1,N+1);
y=zeros(1,N+1);
x(1)=0;
y(1)=293;
for n=1:N
x(n+1)=x(n)+h;
ybar=y(n)+h*dyfun(x(n),y(n));
y(n+1)=y(n)+(h/2)*(dyfun(x(n),y(n))+dyfun(x(n),ybar));
end
plot(x,y,'red');
function m=dyfun(x,y)
m=1/304+75/19*(1773-y)+(6.804e-8)/304*(1773^4-y^4);

To create a new file in Matlab writing these codes and save it. Input some properties, for example eulerg(0,293,0.001,1000), and you will gain the relationship line between ‘y’ and ‘x’.

You can transfer this example in any other similar work process by just change some part of this example function. I’m glad to discuss with you if you have any questions.