| 1. |
- Gao, Chuansi, et al.
(författare)
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Moisture absorption, mass loss and evaporative resistance of permeable clothing in a transient condition
- 2006
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Ingår i: Journal of Donghua University. - 1672-5220. ; 23:5, s. 54-58
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Tidskriftsartikel (refereegranskat)abstract
- The water vapour resistance of clothing ensembles is not as commonly determined as dry thermal insulation. The measurement techniques are more complicated and the measurement values differ among laboratories. Due to complicated moisture transfer process through clothing ensemble, the moisture absorbed and evaporated varies in transient and steady state phases depending on properties, thickness of clothing, and environmental conditions. The purpose of this study was to measure moisture absorption inside hygroscopic underwear, hydrophobic and permeable outer wear as a function of time, to investigate mass loss from “skin” as well as from manikin, to quantify evaporative heat loss and total heat loss from manikin, to determine evaporative resistance of clothing. Manikin Tore was used by wearing wet “skin” to simulate sweating. Moisture content gain of the inner garment shows an exponential relation against time. Moisture in the outer permeable garment shows very small gain. On the contrary, mass loss directly from the wet skin decreases exponentially. The mass loss from the manikin is relatively stable throughout three test phases. The evaporative heat loss is about two thirds of the total heat loss from the sweating manikin. One hour measurement time is sufficient to get stable results while measuring the evaporative resistance of clothing ensembles with hygroscopic inner garment and permeable outer garment. The variation between the 1st hour and the 3rd hour is less than 5%. The length of transient period and measurement time requirement is dependent on the permeability, thickness of clothing ensembles and environmental conditions.
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| 2. |
- Zhou, Ya S., et al.
(författare)
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Study of Performance on Recharging the Borehole by Means of Exhaust-air Energy
- 2009
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Ingår i: Journal of Donghua University (English Edition). - 1672-5220. ; 26:2, s. 126-131
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, the performance analysis of recharging the borehole by means of exhaust-air energy is carried out. The results show that a vertical borehole used as heat source for a Ground Source Heat Pump (GSHP) can be recharged in high efficiency. With equal heat transfer capabilities of exhaust-air coil and borehole collector, the system provides a maximum overall efficiency. However, due to ground infinite capacity, the optimum brine flow rate is different from conventional two-exchanger system. The recharging system provides two peak overall efficiencies when the capacity ratio Cr = 5 for laminar flow and Cr = 15 for turbulent flow respectively. The overall efficiency is independent of exhaust-air temperature and undisturbed ground temperature, although the fluid properties depend on temperature. In practical system lower ethyl percentage brine should be chosen if the freezing point meets the system request, which can provide a higher overall efficiency.
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