Describes a simple, inexpensive sampling technique for infiltration measurement using SF6 tracer gas. Uses pre-evacuated blood collecting test tubes with rubber stoppers for sampling. This is controlled by a micro-processor driven automatic sampler, which drives a hypodermic needle through the rubber stopper to fill the tube with an air sample. Analyzes samples using a gas chromatograph. Releases SF6 at ground level in a high-rise cold store and collects samples of air at different heights to see if stratification is present.
Measures air exchange across open cold store doors using an anemometer and by tracer decay methods. Anemometer results show that an empirical factor of 0.68 should be applied to the predictive equation by Tamm. Observes a further reduction in air change rate (about 47% reduction) due to imperfect mixing of the air. Air curtains reduce infiltration by about 75-80% and plastic curtains by approx. 93%. Forklift traffic and internal circulation fans also affect air change rate.
Uses a two-region model to predict infiltration, to take into account non-ideal mixing of tracer gas in a building. Considers versions of this model:< 1. Fluid flows between the 2 regions and the environment in any manner provided steady state and mass balance are maintained.< 2. There is limited interchange between the regions< 3 Air flows into the first region and out of the second with (unbalanced) interchange between the two.< 4. The second region is a "dead-water" zone, which is not directly connected with the outside.<5.
Describes different goals of air leakage measurement with corresponding measuring methods. Discusses results and experience from measurements carried out with the stationary overpressure method and the non-stationary tracer gas method. Adds working diagrams. Pleads for further standardisation of thespecific equivalent leak opening (SELO) especially of temperature on which it is based. Gives numerical example for calculating the lower limit of admissible non-tightness of cold rooms.
Reports insights from research project "Optimalisatie koelhuisbouw" (Optimisation of cold store buildings) by the Delft Technical University for the Foundation for Cooling Technique Development. Pleads for standardisation of the maximum admissible heat gain by air leakage and yearly averaged pressure differences between the cold room and its surroundings. Gives some numerical examples. Uses theory of specific equivalent leak opening.
Recommends method for determination of extra heat and moisture load of a cold room resulting from leakages through chinks, cracks and porosity. Recommends clause on maximum leakage in delivery conditions. Treats internal and outdoor influences on air exchange, leakage detection and leakage measuring methods.
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