Comparison of Ammonia Emissions from Poultry Houses Based on Diurnal Integration vs. Daily Means of Gas Concentration and Building Ventilation Rate
Quantification of aerial emissions from animal feeding operations (AFOs) requires the knowledge of both concentration of the constituent of interest and the ventilation rate (VR) through the emitting source. Daily emissions can be and are normally determined from diurnal integration of frequent measurements, referred to as the diurnal integration method (DIM), but is resource intensive. Alternatively, daily emission may be more economically estimated from daily means of concentration and VR, referred to as diurnal means method (DMM). In this study, DMM was compared with DIM in determining daily ammonia (NH3) emissions from mechanically ventilated laying-hen, turkey and broiler houses under U.S. production conditions. Results show that deviations in daily NH3 emissions between DMM and DIM methods ranged from as small as < 3% (e.g., for medium age turkey under both cold and warm weather conditions) to as high as 98% (e.g., broiler houses in summer). Deviations were related with coefficient of variation (CV) of VR or NH3 concentration, although prediction of the deviation using CV of VR and/or NH3 concentration alone will likely not produce reliable results. The study suggests that caution must be taken when using DMM to estimate daily NH3 emissions from poultry houses under typical US production conditions.
Effects of diurnal emission patterns and sampling frequency on precision of measurement methods for daily ammonia emissions from animal houses
Ammonia concentrations and airflow rates are the main parameters needed to determine ammonia emissions from animal houses. It is possible to classify their measurement methods into two main groups according to the sampling frequency: semi-continuous and daily average measurements. In the first method, ammonia concentrations and airflow rates are monitored during a certain period and instant emission rates are calculated. When using daily average methods, 24-h average ammonia concentrations and airflow rates are used to determine the average daily emission rate. As less information is used in the second method, an error may be expected. The aim of this work was to determine the nature and magnitude of this error. Three databases containing data from semi-continuous ammonia emissions measurements from different animal houses (pigs, poultry and rabbits) in three European countries (Denmark, The Netherlands and Spain) were used to characterise this error. An average systematic deviation between methods of 1.5% was found. The magnitude of this bias was directly related to the daily variation of ammonia concentration and airflow rate. The magnitude of this bias, and also the random component of the error, were modelled. The developed model adequately described variation in bias in the studied dataset (R2 = 0.85) and can be used as a tool to decide which type of measurement methods can be used.
Assessment of Ground Regeneration around Borehole Heat Exchangers between Heating Seasons in Cold Climates: A Case Study in Bialystok (NE, Poland)
Based on the experimental studies, the process of ground regeneration around the borehole loaded with brine-water heat pumps working exclusively for heating purposes in the period of four consecutive heating seasons in a cold climate was presented. The research was conducted in north-eastern Poland. The aim of the work is to verify the phenomenon of thermal ground regeneration in the period between heating seasons on the basis of the recorded data and to check whether the ground is able to regenerate itself and at what rate. It was noticed that the ground does not fully regenerate, especially during heating seasons with lower temperatures. In the analyzed period, from 22 September 2016 to 12 October 2020, the ground probably cooled irreversibly by 1.5 °C. In order to illustrate and evaluate the speed of changes in the ground, the one’s profile with an undisturbed temperature field was presented for each month of the year. The presented results can be a very important source of information for the analysis of geothermal conditions occurring in the ground. They can be used to verify mathematical models and conduct long-term simulations that allow us to see the complexity of the processes taking place in the ground.