Long term performance of vacuum insulation panels in hybrid insulation district heating pipes

Vacuum insulation panels (VIPs) with a glass-fiber core has been considered to be difficult to operate for a long period of time, such as for building applications, because the thermal conductivity rises rapidly as the pressure increases. However, glass-fiber-core VIPs contain a material called a getter that continuously adsorbs permeated gas, and a theoretical model that considers the properties of the getter has not yet been developed. In this paper, the gas-adsorption mechanism by getters was investigated and a long-term-performance prediction model that considers the temperature dependence was proposed. Some gases were not adsorbed by the getter in the VIPs; however, a model was proposed that takes into account the non-absorbed gases by applying partial pressure to the adsorption isotherm in advance. The long-term performance of VIPs with different areas and volumes was compared with the measured values, and the validity of the calculation results was confirmed. These results show that the long-term performance of VIPs of different sizes can be accurately predicted when the getter performance is well understood.

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Feasibility study of collective heating and cooling based on foundation pile heat exchangers in Vejle (Denmark)

Quarterly Journal of Engineering Geology and Hydrogeology ◽

10.1144/qjegh2020-114 ◽

2020 ◽

pp. qjegh2020-114

Author(s):

D. Cerra ◽

M. Alberdi-Pagola ◽

T.R. Andersen ◽

K.W. Tordrup ◽

S.E. Poulsen

Keyword(s):

Energy Demand ◽

District Heating ◽

Demand Model ◽

Heating And Cooling ◽

Energy Piles ◽

Geophysical Investigations ◽

Foundation Pile ◽

Long Term Performance ◽

Term Performance

We assess the feasibility of a collective district heating and cooling network based on a foundation pile heat exchanger in a new urban area in Vejle, Denmark. A thermogeological model for the area is developed based on geophysical investigations and borehole information. In tandem with a building energy demand model, the subsurface thermal properties serve as the input for a newly developed computational temperature model for collective heating and cooling with energy piles. The purpose of the model is to estimate the long-term performance and maximum liveable area that the energy piles are able to support. We consider two case studies where residential and office buildings dominate the building mass. We find that three to four floors can be supplied with heating and cooling from the energy piles, depending on the use and design of the buildings.

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Study on the temperature dependence of gas permeation and adsorption behavior of the vacuum insulation panel with getter materials

E3S Web of Conferences ◽

10.1051/e3sconf/202017221001 ◽

2020 ◽

Vol 172 ◽

pp. 21001 ◽

Cited By ~ 1

Author(s):

Hideya Yamamoto ◽

Daisuke Ogura

Keyword(s):

Thermal Conductivity ◽

Temperature Dependence ◽

Pressure Sensor ◽

Glass Wool ◽

Adsorption Behavior ◽

Vacuum Insulation ◽

Long Term Performance ◽

Term Performance ◽

Vacuum Insulation Panel

Vacuum insulation panel (VIP) is a high-performance heat insulation material that has contributed to the energy efficiency of refrigerators, vending machines, and cooler boxes. Glass wool or fumed silica covered by a laminated film are the core materials of VIP; by evacuating air inside, it is possible to reduce the gas thermal conductivity to be close to 0 and exhibit high thermal performance. In recent years, the research on long-term performance prediction has been conducted for use in building insulation. Specifically, various getter materials have been developed to improve the long-term performance of glass wool VIP. However, there are no studies that clearly show the adsorption behavior or temperature dependence inside VIP with getter materials. We measured the adsorption temperature dependence of two types of getters using the constant volume method and then observed the adsorption behavior inside VIP using VIP equipped with a micro pressure sensor. Regarding the internal pressure of VIPs equipped with the micro pressure sensor, the pressure fluctuation derived from the adsorbent was confirmed by the temperature change, and it was confirmed that the thermal conductivity changed accordingly. If the internal temperature of VIP increases, gases may be released from the getter. Therefore, in the building environment, it is necessary to select a getter that is suitable for the usage environment and to use an appropriate amount of getter.

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