Vagn Korsgaard

Dimensioning of the solar heating system in the zero energy house in Denmark

Abstract The paper describes the project for a Zero Energy House constructed at the Technical University of Denmark. The house is designed and constructed in such a way that it can be heated all winter without any “artificial” energy supply, the main source being solar energy. With energy conservation arrangements, such as high-insulated constructions (30–40 cm mineral wool insulation), movable insulation of the windows and heat recovery in the ventilating system, the total heat requirement for space heating is calculated to 2300 kWh per year. For a typical, well insulated, one-storied, one-family house built in Denmark, the corresponding heat requirement is 20,000 kWh. The solar heating system is dimensioned to cover the heat requirements and the hot water supply for the Zero Energy House during the whole year on the basis of the weather data in the “Reference Year”. The solar heating system consists of a 42 m2 flat-plate solar collector, a 30 m3 water storage tank (insulated with 60 cm of mineral wool), and a heat distribution system. A total heat balance is set up for the system and solved for each day of the “Reference Year”. Collected and accumulated solar energy in the system is about 7300 kWh per yr; 30 per cent of the collected energy is used for space heating, 30 per cent for hot water supply, and 40 per cent is heat loss from the accumulator tank. For the operation of the solar heating system, the pumps and valves need a conventional electric energy supply of 230 kWh per year (corresponding to 5 per cent of the useful solar energy).

The Wick-concept for Thermal Insulation of Cold Piping:

The wick-concept for thermal insulation of cold piping is based on capillary suction of a fiber fabric to remove excess water from the pipe surface by transporting it to the outer surface of the insulation. From the surface of the insulation jacket, the water will evaporate to the ambient air. This will prevent long-term accumulation of moisture in the insulation material. The wick keeps the hydrophobic insulation dry, allowing it to maintain its thermal performance. The liquid moisture is kept only in the wick fabric. This article presents the principle of operation of cold pipe insulation using the wick-concept in either of two variations: the self-drying or the self-sealing system. Experiments have been carried out using different variations of the two systems to investigate the conditions for exploiting the drying capabilities of the systems, and the results are presented. The results show that the variations of these types of insulation systems work for pipes with a temperature above 0 C and for ambient conditions within common ranges for industrial applications.

Innovative Self-Drying Concept for Thermal Insulation of Cold Piping

In the paper an innovative Self-Drying concept, the Hygro-Wick concept, for thermal insulation of cold piping is described. The concept is based on the wicking action of certain fabrics to remove by capillary suction condensed water vapour from the pipe surface to the outer surface of the insulation/jacket, from where it will evaporate/diffuse into the ambient air. Hence the concept will prevent long term accumulation of moisture in the insulation material. Theoretical and experimental results for two different embodiments of the concept is given: The Self-Drying system and the Self- Sealing system.

Novel Innovative Concept for Self-Drying of the Insulation of Cold Piping

The self-drying concept for the insulation of cold piping is based on the wicking action of a hydrophillic fabric which is wound around the pipe and ex tended through the slot of the tubular insulation mantel. If the dew point of the am bient air is below the temperature of the surface of the pipe, water vapour will diffuse through the insulation, condense on the pipe and be sucked up by the wick fabric and transported by wicking action through the slot to the surface of the insulation mantel, from where it will evaporate into the ambient air. In this paper, an experimental set-up is described which within a few hours can demonstrate the self-drying concept. Results are given that show that the concept is able to prevent moisture build up in tubular mineral fibre insulation even without any vapour retarder jacket. The concept can also be used on piping below freezing temperature if the cooling plant is closed down for a short period once a year or every other year, depending on the permeability of the vapour retarder jacket.