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  1. #1
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    New Method for Compressor Load Modulation

    I would be interested in comments relating to the potential pitfalls of this innovation and next steps.

    Essentially the aim is to build a compressor with an efficiency similar to scroll compressors at a lower price point- something that could be attractive in price conscious developing markets.

    The innovation basically alters the stroke length of a reciprocating piston compressor using a unique control connection driven by a brushless DC motor. The load can vary from 20% to 100%.

    Naturally there are numerous disadvantages with recips such as vibration and noise, but equally they are very useful for high pressure needs.

    At first this sounds expensive and complex however the price of brushless DC motors has collapsed due their use in drones and really, all that is needed is a 24v supply and sufficient logic to advance and reverse the motor according to a position sensor and temperature probe.

    The mechanism is exact and easy to implement (unlike many forms of inlet valve modulation) and has the advantage of not only being able to track temp and humidity as closely as a 2 speed or even pulse width modulated scroll but the start up load of 20% is handy in lowering in-rush current. Naturally it would benefit from a VFD but the aim is to provide good efficiency at a low price.

    The unit is larger than a standard recip. There may be issues in lubrication at low rpm.

    I would welcome any comments based on people's experience. Where I live (Australia) the most common residential units are rotary compressors with inverters. Few people can afford scroll based compressors of any kind. I think emerging markets would be attracted to this new design based on build cost and relatively good efficiency.

    My belief is that recips are easier to build cheaply since they don't require the machining tolerances of scrolls and the electronics of inverters. Hence rotaries are a good compromise but are not popular in very large units.

    I have been involved in inventing (unsuccessfully) for a while. I built an alternating valve from polypipe (20 mins in the shed) Please google alternating valve and look for 2 youtube videos.

    it has a single moving part and has been running in my garden for 2 years without a break.

    That invention was a cheap alternative to the galcon alternator valve (google it too).

    I approached 3 australian manufacturers about this valve. One just wanted to know how it worked but in the end offered a very frank understanding of the realities of bringing things to market. In retail u have to convince a chain store to take something off the shelf in order to put yours on. Of course people can market online and do, but without real demand it is just an ego exercise and not how inventors want to spend their time.

    The second manufacturer signed an NDA and assessed it but viewed the demand as too low to bother with.

    The third manufacturer would not sign an NDA since they claimed they had been sued in the past for things they saw but had been working on anyway.

    I have also looked at applications in hydraulics and pneumatics but again see little need for a very neat, robust as a brick, cheap innovation that only met a need I had and which already exist but at a higher price point.

    So I assume I will get similar treatment with this innovation. Many companies will not touch any external IP except on terms that are insane. For example, the Honda marine group has a web page that says you can send any innovation you like but (a) they don't have to acknowledge they received it (b) they can do whatever they like with it including making money. Rotax Bombardier- the engine maker- had similar conditions but in addition (up to 2 years ago) you sent paper copes of plans to a PO Box in Canada!

    It is increasingly true that companies only want to know about their internal IP development and not that of others unless the conditions are extortionate. For example the innocentive people (google innocentive) set up competitions for prizes in the 30K range for innovations that would be worth millions if patented.

    Anyway I would appreciate any practical comments/advice about this method of load modulation from people in the industry and also those who may have commercial experiences in bringing innovations to market.

    Thank you.

  2. #2
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    Sounds like the new Infiniti variable compression motor turned compressor.

    Sent in a state of increasing entropy using Tapatalk

  3. #3
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    Thread Starter
    Quote Originally Posted by R600a View Post
    Sounds like the new Infiniti variable compression motor turned compressor.

    Sent in a state of increasing entropy using Tapatalk
    You have a good sense for the concept however u should note that most variable compression approaches in internal combustion engines vary the displacement by only small amounts since the range of compression ratios is very small e.g. maybe 8: 1 to 15:1. On the other hand this innovation varies from 10% to 100% displacement.

  4. #4
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    Agreed. All i can say is hurry up and produce it because i want to buy it.

    Sent in a state of increasing entropy using Tapatalk

  5. #5
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    I volunteer to test your compressor in my system for free.

    Sent in a state of increasing entropy using Tapatalk

  6. #6
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    Quote Originally Posted by Dreyfus View Post
    You have a good sense for the concept however u should note that most variable compression approaches in internal combustion engines vary the displacement by only small amounts since the range of compression ratios is very small e.g. maybe 8: 1 to 15:1. On the other hand this innovation varies from 10% to 100% displacement.
    It just got 10% better.

    Sent in a state of increasing entropy using Tapatalk

  7. #7
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    Since I commented the other day I've been thinking about your question and your situation because I had a hard time understanding why you wouldn't use primarily Scrolls in your area.
    I think I may have come up with one reason if I'm not mistaken it gets quite hot in the summer and rotary compressors are not vapor cooled. The reason I mention that is with a rotary compressor that is not vapor cooled you're able to make a higher efficiency unit for much cheaper. That is why they're quite common in window units. The condenser coil can be much smaller.

    Sent in a state of increasing entropy using Tapatalk

  8. #8
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    Rotary compressors are highly efficient. Only reason they were not used in larger systems is the vanes wear and leak too quickly. Now we are starting to see larger systems like the Bosch resi unit on a variable speed control. Apparently Mitsubishi has overcome the rotary's limitations... If so, we may start seeing these used in larger systems and refrigeration systems. All piston compressors suffer from adibatic losses. This is why scrolls and rotary's are taking over the market.
    A dying culture invariably exhibits personal rudeness. Bad manners. Lack of consideration for others in minor matters. A loss of politeness, of gentle manners, is more significant than is a riot.
    ― Robert A. Heinlein

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