The water heat pump systems by utilizing the existing snow-melting equipment were constructed to reduce heating costs in the snowy region. In addition, the effect of introducing these systems was evaluated by reducing heating costs and CO₂ emission. The results are as follows: (1)Groundwater temperature for snow melting is 8.9 ℃ on average without significant variation during the measurement period. The temperature was confirmed to be stable as heat source of water heat pumps. (2)The temperature range in the greenhouse by using the water heat pump systems was controlled to be the same range obtained by using boiler system with a preset temperature of 20 ℃ and a corresponding oil consumption of 47.2 L/d. (3)The results showed that the water heat pump systems could reduce 54.3 % at the maximum of the heating costs during the investigation period, comparing with the boiler system. (4)Water heat pump systems could reduce 12.2 % of the running costs which include running costs for snow melting. (5)The relationship between the benefit of the introduction of the systems and the operating time of snow melting (snow melting operation rate) was analyzed. The results showed that the maximum reducing rate of the running costs was 21.8 % when the COP and the snow melting operation rate were 3.38 and 70 %, respectively. (6)The relationship between the benefit of the inｔroduction of the system and the monthly heating load was analyzed. The results showed that the maximum reducing rate of the running cost was 21.9 % when the heating loads was under 127.0 W per square meters and the snow melting operation rate was 95 %. (7)The influence of the oil price on the benefit of the introduction of the systems was also analyzed. Regardless of the snow melting operation rate, it is found that the running cost in these systems is lower than in boiler system when the oil price is over 64 yen per liter. (8)The results showed that the CO₂ emission was reduced by 10.8 % by using present system, comparing with the boiler system. Therefore, the above results show that the water heat pump systems constructed in this study are efficient for the greenhouse heating in the snowy region.

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In a cold area (Sakata. Japan), a ground source heat pump system and an air source heat pump system for greenhouse heating were compared. Results obtained were as follows. 1)Air temperature of a greenhouse equipped with the ground source heat pump system was maintained at heating set point (14 ℃). On the other hand, air temperature of a greenhouse with the air source heat pump system could not keep the same set point, and it ranged from 7 to 14　℃. This suggests that heating capacity of the ground source heat pump system was 67 % higher than the air source heat pump system, which had the same official compressor output as the air source heat pump system. 2)System COP of the ground source heat pump system was stable and its average was 3.89. Using average hourly heat transfer coefficient obtained from the analysis of the ground source heat pump system, system COP of the air source heat pump system was evaluated. And it ranged from 1.8 to 2.5 and its average was 2.14. 3)Compressor electric power consumption of the ground source heat pump system was over 30 % less than the air source heat pump system. Although total electric power consumption of the ground source heat pump system contained not only compressor and condenser fan-coil, but also circulation pump, it was 22 % less than the air source heat pump system.

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Using highly dehumidified cool air for drying cereal grains while preserving grain quality was investigated. A dehumidified air dryer comprised of an air compressor and a dehumidifier with a Peltier element was used to dry barley and wheat grains under a humid climate condition. In an additional experiment, the quality preservation of aromatic rice was examined. Results showed that the dryer could produce cool and dry air as comparable or lower humidity than those reported in previous studies. The relative humidity of outlet air (17.2 %,RH) was 57.7 % lower than that of inlet air (74.9 %,RH) at the airflow rate of 5 L/min. The humidity difference between the inlet and outlet air decreased roughly in proportion to increasing airflow rate of the dryer. The moisture content of barley decreased at the same drying rate in the moisture content ranged from 35 %,d.b. to 15 %,d.b. when the airflow rate was 5 L/min and 20 L/min. The drying rate was slow down in the moisture content below 15 %,d.b. in the airflow rate of 20 L/min compared with the airflow rate of 5 L/min. However, it might not be evident whether there was not much difference in the drying rate when the airflow rate was changed because all dehumidified air condition except airflow rate was not the same in this experiment. The effect of preserving the aroma component AcPy was examined by changing the air temperature condition. The dehumidified air dryer could maintain the AcPy content of aromatic rice at the same level as the initial concentration.

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We investigated the vacuum drying characteristics of kiwifruit slices (approximately 10 mm thick). The experiments were conducted in a vacuum chamber with pressures ranging from 1.33 to 2.00 kPa and at five drying temperatures ranging from 30 to 70 ℃. We also investigated shrinkage, which refers to changes in the volume and surface area of the sliced kiwifruit during vacuum drying. The volume ratio was represented as a linear function of the moisture content, and the surface area ratio was approximated by a power function of the moisture content based on the relationship between the volume ratio and moisture content. Using the shrinkage data, we modeled the drying characteristics of this fruit. The empirical changes in moisture content agreed well with an exponential model for the first falling-rate period and Page’s model for the second period.

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Numerous pipe-framed greenhouses (referred to as “pipe houses” hereafter) were damaged by tornados in Ibaraki and Tochigi Prefectures on May 6, 2012. We surveyed damaged pipe houses along the tracks of two tornados, and determined the relationship between the modes of failure of pipe houses and wind direction. Light-weight pipe houses do not have sufficient wind resistance to withstand a tornado that is F1 or more on the Fujita scale of tornado intensity. For wind direction perpendicular to the ridge, collapse was such that the windward side walls and eaves were pushed down. This collapse mode resembled that of a Typhoon blowing normal to the ridge. Pipe houses were destroyed by the wind in the horizontal direction in the circumference, rather than by the upward flow near the center of the tornado. The influence of the difference of covering film or structure on the collapse mode was not significant. In many cases, all types of covering films were not blown off in the wind. There was not enough time for the covering film to fail, because the wind velocity increased in an exceedingly short period. Therefore, the covering film transmitted the wind pressure on its surface to the frame of the pipe house causing it to fail. For wind parallel to the ridge the pipe house collapsed along the direction of its ridgeline. To avoid this inclination, it is necessary to increase the number of bracing elements and to modify the connections to prevent rotation of the arch pipe and the straight pipe elements crossing at a right angle.

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