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Thread: Photovoltaic to heat water vs solar water heater

  1. #16
    General Engineering Contractor ballvalve's Avatar
    Join Date
    Dec 2009
    northfork, california


    We are going to get a lot of MFG back because of low energy costs and the number of workers that would take 8 or 10 bucks an hour after getting tired of going to the free canned food handout shops. And the huge costs of co-ordinating with a factory 10,000 miles away. I think most compressors have turned to crap. I took out the thermostat in my 20 year old chest freezer many years ago, and it maintains -12' [!] My food lasts forever, and the compressor love to run full time. But rotary screw compressors are very hard to make cheap because of the tolerances and oil issues. At least with my experience with AIR compressors.


    Faribault, Minn., is a long way from Silicon Valley, and Faribault Woolen Mill Company may be a far cry from the typical startup. But when cousins Chuck and Paul Mooty first toured the vacant 147-year-old mill in July 2011, they knew the dilapidated building with a flooded basement and outdated equipment was the kind of business that could spark a manufacturing revival -- even a revolution.

    "What we had here was a great Americana brand -- the oldest manufacturing entity in the state of Minnesota," Chuck Mooty said. "We had a very short window of time to take something and brush it off. We could have thought of all the reasons not to do it, but we took a leap of faith. We just had the feeling that someone had to step up and bring this thing back."

    Chuck and Paul Mooty aren't the only ones giving manufacturing another shot. When President Barack Obama, in his State of the Union address, touted "an economy built on American manufacturing" and acknowledged the "huge opportunity at this moment to bring manufacturing back," manufacturing went from boring to buzzword overnight.

    But Obama's examples of manufacturing success -- auto companies and Master Lock -- represent the old-school era of manufacturing. Instead, small manufacturers like Faribault and entrepreneurial thinkers like the Mootys may be the key to transforming manufacturing as we know it and bringing jobs back to the United States that big businesses handed off to foreign countries decades ago. Some experts believe that in this new wave of manufacturing, small businesses will be better able to compete with countries like China and with big U.S. companies, thanks to consumer demand for "made in America" products, groundbreaking technology, and the flattening of the global cost curve in terms of wages and production methods.

    Vivek Wadhwa, academic, researcher, writer and entrepreneur, has no doubt that within two decades, the United States will return to manufacturing supremacy.

    "China has, at the most, 10 years to enjoy the money it's making off manufacturing," Wadhwa said. "In the next five to 10 years, we'll see a major disruption happening in China, and in 10 to 20 years, there will be a hollowing out of China's manufacturing industry, just as there was in the U.S. If I were China, I'd be losing sleep right now."
    Last edited by ballvalve; 05-11-2012 at 12:21 PM.

  2. #17
    In the trades Dana's Avatar
    Join Date
    Jan 2009


    I agree that a lot of manufacturing that had been pushed to China will be coming back or going elsewhere for a number of reasons, but it remains to be seen what the net effect will be for the US labor force. I'm not hopeful that that manufacturing sector growth in the US can soak up the labor surplus- this is one of those difficult eras not too different from when agriculture became highly industrialized, and in the course of a few decades saw a permanent reduction in force greater than 75% (now greater than 90%.) For every 10 jobs that went to China when production left US shores, even if that production returns it won't add those 10 jobs back- it'll be 2-3 if we're lucky. The rapid growth in manufacturing productivity in the US since 1980 keeps US products competitive on the world market, but has reduced the total employment in the manufacturing sector in ways unrelated to the job-exports.

    China is indeed too dependent on exports, and will be up a creek if they don't develop internal markets. The US won't "return to manufacturing supremacy", it never lost manufacturing supremacy (by just about any metric), even with the wholesale export of entire industries offshore. But US growth in manufacturing hasn't had a commensurate increase in the number of US manufacturing jobs due to even faster growth in US productivity. China too is becoming more automated as internal labor rates rise, and that's happening at a much faster rate than it did in the US. Employment numbers are indeed keeping the party insiders up at night- without double-digit economic growth it becomes a very dangerous place for them. That's not to say that China's labor-pool issues are going to be a direct benefit to the US work force though.

    So while the bailout may have "saved" Detroit manufacturers, it hasn't saved Detroit. The auto making work force was already much diminished from it's 1980 numbers, and the retrenchment hasn't and WON'T return the workforce back to it's pre 2008-crash size, ever.

    Compressors for HFCs like R410A don't have the same seal & lubrication issues that air compressors do- they're much larger and more viscous molecules. Most rotary air compressors are not scroll designs. Even sloppier-toleranced scroll compressors aren't cheap, but they have fewer moving parts and better longevity and better performance than cheaper old-school reciprocating compressors (especially poorly made ones) and other rotary compressor types. The huge Asian market for space heating/cooling heat pumps has parts-and-cost reduced the 1-3ton refrigeration scroll pumps over the past 20 years. Ductless heat pumps currently hold something like 90% of the home heating market in Asia- they've gotten both cheaper and BETTER since they were invented ~35 years ago, with huge improvements in performance with the advent of scroll compressors with variable speed drive, and variable refrigerant volumes that are controlled via digital feedback algorithms. They're far more complex than your 1-ton window-shaker, but they have fewer mechanical parts, yet more (and more reliable) electric & electronic components, from the DC power supplies and inverter drive DC motor controls to optimized control algorithms. (At least the micro-controllers inside aren't running WinDoze, eh? Or ARE they... ;-) )

    IIRC Fujitsu manufactures a lot of the compressors and electromechanical parts (like the refrigerant flow valves) for a lot of other ductless manufacturers, but there's much more to getting the efficiency out of them than these few critical components.

    SFAIK nobody makes a scroll compressor capable of using CO2 as a refrigerant (yet) due to the high pressure/small molecular size, but as a refrigeration technology for space heating CO2 is likely to become common in the coming decades. It's cheap stuff to manufacture and handle, and has but a tiny fraction of the greenhouse gas potential of HFCs like R410A (the currently favored refrigerant being touted as a "green" refrigerant, due to lower greenhouse gas & ozone depletion potential compared to R22 & R12.) Sanyo is currently selling air-to-hydronic CO2 refrigerant space heating units, primarily in Europe, but also in Japan. It uses a 2-stage rotary compressor, but it's not a scroll-type. It's similar to the a Wankel rotary automotive engine at it's most-basic description, with some special valving to make give it 2-stages without adding a lot of vibe. At ~130F water temp output temps with a big delta-T it still has a COP of ~2 @ +20F outdoor temps, and even at -4F it's still performing better than 1.5. At lower output temps lower than domestic hot water it does even better. The biggest one puts out ~31KBTU/hr @ +5F, with 130F output which is enough for many or most European single family homes, and more modestly sized or better insulated US housing stock. (I could use it to heat my house as-is at +10F, but would be starting to lose ground by +5F. A ductless R410A mini-split would deliver better seasonal efficiency for me, but that would cost more to run than the existing gas-fired system.)

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