Abstract
Recently, the heat load for space heating in residential houses has been reduced as airtightness, and thermal insulation performance has been improving even in moderate climate regions of Japan. In such situations, the heat load can be handled by one room air-conditioner with high energy efficiency. We report the results of computational fluid dynamics (CFD) analysis of an indoor thermal environment and the airflow distribution during the space heating operation in a ductless house air conditioning system, in which heated air from a room air conditioner installed in a thermal-insulated basement space is distributed throughout the building using air inlets on the floor in each story and open-door rooms without ductworks. To determine the adequate size and position of the air inlets on the floor in this heating system, we evaluated the air circulation performance for changes in the conditions of the air inlets by CFD analysis for a standard two-storey house model in Japan. The results suggest that the air temperature distribution is markedly different in the size and position of the air inlets on the floor. Large volumes of airflow through the openings in the building resulted in maintaining the rooms at a temperature range of 17 to 24 degrees uniformly. These results also provide information for system and building designs for effective space heating and for proper usage when choosing to open or close air inlets in the operational phase.
Highlights
Japanese space heating systems are different from European systems
We report the results of computational fluid dynamics (CFD) analysis of an indoor thermal environment and airflow distribution during the space heating operation in this heating system
We evaluated the air circulation performance for changes in the air inlet conditions by CFD analysis for a standard two-storey house model in Japan to determine the adequate size and position of the air inlets on the floor in the heating system
Summary
Japanese space heating systems are different from European systems. In North and Eastern Europe, district heating systems, which currently have a 10% share in the EU, have significant market penetration. Central and Southern European countries have an almost non-existent market [1] [2]. Air-to-air heat pump systems are among the most widespread in buildings in most south European countries, in those without any other heating system, since they are used for both heating and cooling. They are much more energy-efficient than other types of electric heaters, especially in regions with mild winters [5]
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