Nick Pine — alt.solar.thermal / alt.energy.renewable / sci.engr.heat-vent-ac — July 26, 1995
Source URL: http://www.ibiblio.org/london/renewable-energy/solar/Nick.Pine/msg00008.html
Nick Pine (Villanova University, [email protected]) quotes extensively from Steve Baer's Sunspots in a 1995 Usenet post.
From his 1979 Cloudburst Press book, ISBN 0-88930-062-3, pp 62-66, Sunspots "An Exploration of Solar Energy Through Fact and Fiction."
This confirms a 1979 Cloudburst Press edition of Sunspots — distinct from the 1975 Zomeworks Corporation first edition. The subtitle differs: "An Exploration of Solar Energy Through Fact and Fiction" vs. the 1975 "Collected Facts and Solar Fiction." The archive holds only the 1975 edition.
Baer opens by noting institutional skepticism toward convective systems:
Much work still needs to be done on the behavior of convective air loop rock storage systems. The way they work flies in the face of the typical air conditioning engineer who can't believe such systems could operate without fans. At a solar energy conference in 1968, Farrington Daniels mentioned the letters he had received from someone in New Mexico building solar chimneys that pushed air through rock storage bins. He was told by an engineer in the audience that the chimneys would have to be as tall as the Empire State Building. I was very pleased to report on the performance of the just-completed Drop City heater where the chimney was only 14 feet high.
Paul Davis house (Corrales, 1972): heated by a convective air loop, no fans. Los Alamos engineers who dismissed these systems "had never actually experimented with any rocks, but instead were using only computer simulations."
Zomeworks 1969 experiments: 750 BTU/sq ft/day average storage in December Albuquerque weather, with collector and storage bin at the same elevation.
A solar chimney is a sloping glass-covered channel. Air heated in the channel rises (chimney effect). The pressure difference driving the loop:
Example: 8-foot chimney, average rising-air temp = 130°F, average descending (storage side) temp = 90°F.
This is extremely low — standard engineering tables rarely give flow data at such resistances.
Self-balancing: The chimney temperature rises until airflow increases enough to carry away collector heat. Poor design (high resistance) forces the system to overheat to get enough flow, increasing collector losses.
Five layers of expanded metal lath as heat exchanger:
Baer notes further work in UN Solar Energy publications (vol. 5) and by Dunkel (Australia) and Scott Morris (Santa Fe, NM).
Source: Nick Pine, "Steve Baer on Air Loop Rock Storage Systems," Usenet post to alt.solar.thermal, July 26, 1995. Archived at ibiblio.org.
URL: http://www.ibiblio.org/london/renewable-energy/solar/Nick.Pine/msg00008.html