Nobuo Nakahara

Experimental study on house cooling and heating with solar energy using flat plate collector

Abstract The OSE Project aims at developing the technology to utilize solar energy for heating, cooling and hot water supply on the basis of various technology for energy conservation in buildings. For the first step of this project a solar heating and cooling system with flat plate collectors and absorption refrigeration machine was installed in a house in 1974. This paper reports outlines of the system and operating results.

Thermal performance and pressure drop of rock beds with large storage materials

Abstract In air-based solar heating systems, the fan power needed to overcome friction loss in rock beds can reduce the benefit of the system. The system performance of rock beds with large-sized storage materials that have comparably low friction loss is studied. A theoretical model of the heat transfer process within the rock bed is developed for large storage materials. In this model, the temperature within the materials is assumed to be distributed quadratically and symmetrically at their center. The relationship between the model parameter and the air flow rate was derived from experimental measurements for some large materials as well as the pressure drop through the bed. The energy performance of heat pump solar systems with rock beds of various storage materials are studied by the computer simulation under Japanese winter weather conditions. It is concluded that the possibility exists for some large-sized storage materials to have almost the same performance as small-sized materials for heat pump solar systems.

The effects of hypobaric conditions on man's thermal responses

Abstract Hypobaric conditions, with pressures about 30% below that at sea level, are often experienced at mountain resorts. The diffusive transfer of water evaporation increases at hypobaric conditions whereas dry heat loss by convection decreases. Two experiments were conducted to clarify the interactive effects between barometric and thermal events on mans thermal comfort. The experiments were conducted in a decompression chamber where the temperature was controllable. The temperature conditions were set at a constant 26°C or 30°C with 50% RH and 0.1 m/s airflow. The barometric conditions were examined stepwise for 1000, 2000, 3000 and 4000 m of simulated altitudes, which were held for 20 min at 26°C and 40 min at 30°C, respectively. Three male adults, lightly clothed, participated in each experiment. They remained sedentary for about four hours in the chamber. Thermal sensations were measured at each altitude with SD-rating scales. Subjects were also required to complete an introspection. The main results are as follows: when the altitude rose, (1) the heart rate increased for both temperature conditions: the increment at 26°C seemed to be based on hypoxia; (2) the skin temperatures of face and trunk were higher than those of extremities for both experiments; (3) thermal sensations for the face and trunk became warmer for both experiments, so subjects found it difficult to express their thermal state. Therefore, it is supposed that the blood flow in the body would change to compensate for hypoxia under hypobaric conditions.