Heat distribution by natural convection

Natural convection between spaces in a building can play a major role in energy transfer. Two situations are investigated: convection through a single doorway into a remote room, and a convective loop in a two-story house with a south sunspace where a north stairway serves as the return path. A doorway-sizing equation is given for the single-door case. Detailed data are given from the monitoring of airflow in one two-story house and summary data are given for five others. Observations on the nature of the airflow and design guidelines are presented

Natural air motion in passive buildings

The nature of natural convection is described, and a design chart is presented appropriate to a simple, single-doorway situation. Natural convective loops that can occur in buildings are described and a few experimental results are presented. Observations of stratification are discussed, similitude experiments are described, and the beginnings of a complete-system mathematical model are presented

Performance evaluation of the Balcomb solar house

Additional instrumentation was added to the Balcomb solar house for a six-week period and up to 85 channels were recorded hourly. Some new findings based on an evaluation of these data are presented. (1) The thermal comfort characteristics of four rooms are documented. (2) Relative humidity in the living room varies from 30 to 50%; these data are used to infer an evaporation rate in the house of about 25 kg of water/day. The evaporation rate correlates reasonably well with greenhouse temperature. (3) Heat storage in the greenhouse floor is estimated at about 0.30 kWh/day-m/sup 2/ based on temperatures measured at four depths. (4) Several thermal characteristics of the rock bed are deduced but it is evident that the heat flow is not yet completely understood

CRYOGENIC FLUIDS IN NUCLEAR PROPULSION SYSTEMS

Nuclear rocket engines employ hydrogen, a cryogenic liquid, as a propellant in order to obtain a system with a high specific impulse. Since hydrogen is also an excellent moderator of neutrons, it provides a reactivity contribution which must be taken into consideration in the design of a reactor and in its programmed operation. The reactivity worth of hydrogen is a function of its density distribution. The prediction of this quantity was facilitated by heat transfer experiments, which were simulated on a digital computer. Pressure oscillations associated with the twophase flow of hydrogen were simulated by means of a spring-mass model. (auth

Buildings in a Test Tube: Validation of the Short-Term Energy Monitoring (STEM) Method (Preprint)

This paper is extracted from a full-length technical report that presents a detailed analysis of the differences in thermal performance between the SIP and frame units and describes the validation of the STEM method

Passive solar applications

Passive solar applications in buildings are described. The major emphasis of the research has been on devising mathematical models to characterize heat flow within buildings, on the validation of these models by comparison with test results, and on the subsequent use of the models to investigate the influence of both various design parameters and the weather on system performance. Results from both test modules and monitored buildings are discussed. Simulation analysis, the development of simplified methods, and systems analysis are outlined. Passive solar potential in China is discussed

Energy savings obtainable through passive solar techniques

A passive solar energy system is one in which the thermal energy flow is by natural means, that is by radiation, conduction, or natural convection. The purpose of the paper is to provide a survey of passive solar heating experience, especially in the US. Design approaches are reviewed and examples shown. Misconceptions are discussed. Advantages are listed. The Los Alamos program of performance simulation and evaluation is described and a simplified method of performance estimation is outlined

Optimum mix of conservation and solar energy in buildings

A methodology is developed for optimally allocating resources between conservation and solar strategies in building design. Formulas are presented for a constrained optimum in which the initial investment is limited. The procedure is amenable to hand analysis if tables are available which give the Solar Savings Fraction as a function of the Load Collector Ratio for the locality. A numerical example is given