Highlights of the California GeoExchange Project
A two year project sponsored by the Pacific Gas & Electric Company, the California Energy Commission, and the National Geothermal Heat Pump Consortium was initiated in 1997 to increase public awareness, identify California-specific cost-effective technologies, and reduce market barriers for ground-coupled heat pumps. Major activities included demonstration projects, research and development of system and loop designs, and market evaluations. Four commercial projects, and seven single and multifamily residential projects consisting of 326 units, were initiated. Five of these sites were monitored for up to 16 months. Monitoring data were used to calibrate DOE-2 models, which were in turn used to develop performance data for technical evaluations and market studies. Technical evaluations were completed on sizing methods, flow optimization, loop design options, water heating options, hybrid systems, and loop irrigation. Vertical helix loop designs were developed, installed and tested. The project developed 600 pages of reports, including a business plan for GeoExchange in California, and a GeoExchange Handbook. Project recommendations were to distribute key project findings, continue R&D on near term technologies, continue support for R&D to reduce loop costs, and to expand DOE-2 modeling capabilities to accommodate a larger number of system design options.
Monitored ground source heat pump performance in northern California
Fourteen residential ground source heat pump installations in the greater Northern California area were monitored during the period of December 1996 to January 1998. Equipment power, capacity, and efficiency, and loop water temperatures and flow were recorded on a 15 minute basis. Monitoring results were used to calibrate the DOE2.1E hourly building simulation program ground loop model and DOE2.1E was then used to estimate energy savings and life cycle economics for various load, system, and installation configurations.
The parallel waveform relaxation stochastic Runge–Kutta method for stochastic differential equations
For large-scale non-autonomous Stratonovich stochastic differential equations, we study a very general parallel waveform relaxation process which is on the basis of stochastic Runge–Kutta (SRK) method of mean-square order 1.0 in this literature. The convergence of the whole parallel numerical iterative scheme can be guaranteed and the scheme provides better properties in terms of decreasing the load of the computation and operating speed. At the same time, the related limit method is also introduced as the continuous approximation derived from the iterative scheme. In the approximation interval, it is worth noting that the mean-square order of the parallel numerical iterative scheme can be kept consistent with the previous SRK method at any arbitrary time point, not just at discrete points. Some numerical simulations are presented to elaborate the computing efficiency of the parallel numerical iterative scheme.