This paper deals with the determination of several efficiency types of a cross-current recovery exchanger which is a part of the air venting system in the swimming pool hall on the premises of the Czech University of Life Sciences (CULS) in Prague. The product is a cross-current plate exchanger with a heat-exchanging surface of antirust aluminium. According to the manufacturer, the exchanger is fit for temperatures common in air ventilation systems. The air is forced in by fans at a flow quantity of 16,000 m3, maximum speed 2000 rpm, electric motor output 7.5 kW, filters for the air coming from the outside – grade G4, pressure loss from 42 to 200 Pa, filters for the air coming from the inside – grade G3, pressure loss from 46 to 200 Pa. The results presented are derived from in-process measurements taken on 31 January 2007 and 7 February 2007, from 9.15 to 11.30 on both days. Air temperature and air humidity were measured with 9636-51B-type sensors by Ahlborn, connected to the AHLBORN ALMEMO 5990-2 centre. These sensors were placed into each of the four input/output channels, very close to the exchanger itself (Fig. 2). The data measured were saved in the centre ...
When assessing whether it is effective to use evaporation cooling of air in a stable in a particular area, it is essential to have available long-term meteorological data. However, sometimes such data is for various reasons not available. This paper tests a method of generating an artificial series of daily maximum air temperatures from monthly averages. With standard deviation σ (ºC) determined from a statistical analysis of available data and a median expected temperature toc (ºC) obtained from fitting a sine curve through twelve and two monthly average maximum temperatures. The computed values are compared with measured values. The series generated from 12 monthly averages gave better results, although the series from 2 averages would do the job for assessing cooling efficiency. Results of a climatic development model show that around year 2050 the maximum air temperature in June, July and August will increase by 1.8 K, 2.3 K and 3.2 K, respectively, assuming a pessimistic scenario of the growth in greenhouse gas emissions, or by 0.7 K, 0.8 K and 1.2 K, respectively, assuming an optimistic scenario. Based on these values, a series of data was generated for the period around year 2050. It shows that the number of ...
The research is focused on energy sorrel as a fuel for local low-power heating systems with output up to 100 kW. Sorrel is perennial plant surviving in its location nearly 18 years which is very good from the point of crop expenses. It is a robust plant with height of about 2 m in second year of plantation. Dry phytomass is energetically rich fuel with total heating value 17.5 – 18.0 MJ*kg-1 at the average yield of 10 tons per hectare. An experimental combustion of pure sorrel and its blends were done with boiler VERNER A25 – a hot water boiler for pellets. 11 different sorrel fuels consisting of 5 primary kinds were tested during the experiment: sorrel (Rumex tianshanicus x Rumex patientia), Phalaroides arundinacea, Canabis sativa, pine-bark, sorrel (Rumex tianshanicus x Rumex patientia), brown coal. Based on collected data it is possible to obtain an overview of these fuels and their emission properties. Satisfactory values of CO concentration are possible to gain partly by choosing appropriate combustion device and its settings and partly by mixing with other types of fuel. In the case of sorrel the combination of both has been shown very useful. It is very hard to ...
The paper analyses the leakage of air-to-air recovery heat exchanger consisting of 100 capillary thermal tubes 1.5 m long and aligned in ten rows. The operation of the recovery exchanger prototype was tested in a pigsty. The analysis focuses on how the exchanger leakage affects the heat utilisation efficiency of the air ducted from the pigsty, changes in supply/exhaust air flow rate ratio, supply air temperature, thermal output obtained, and exchanger’s total thermal and mass balances. The results obtained in in-process measurements and the mass and thermal balances show that the exchange leakage causes the outside supply air to contain 12.1–37.3% of the pigsty exhaust air. The percentage of the pigsty air increases with the increase of mass flow rates of supply and exhaust air. This leakage resulted particularly in a major change in supply and exhaust air mass flow rates, higher moisture content, temperature and thermal flow of the air conducted in the pigsty. The change in air flow rates resulted in ventilation change so that the overpressure ventilation took place instead of balanced ventilation. This change led to increased thermal losses by air penetrating through leaks in the peripheral building structures. Increased supply air moisture content made it ...
Biomass contains chemical energy which is a transformed Sun radiation. This energy can be used in many different ways. One of these is a direct combustion which is the most popular. The direct combustion of biomass is a technology which is well proven in large-scale heat and power generation. However, the situation in the small-scale heat generation is not so good. This paper describes results from the experimental combustion with various kinds of biomass in three different combustion devices. Saw dust is used in the experiment described below. The aim is to choose the best biofuel modification and the best way for its combustion from the point of view of power and emission parameters. As for the so far reached results of the experiment, the best in case of saw dust is the combustion with gasification of saw dust briquettes on stable grate without primary air or pellets in bottom supplied burner. ...
The paper deals with assessment of thermal fields and temperature changesin ground massif with horizontal heat exchanger used as a heat source for a heatpump. Temperatures in the zone of the horizontal ground exchanger are comparedwith temperatures in a reference land. Changes of heat potential of the soil duringthe heating period are also assessed. Possibilities of recovery of thermal potentialof the ground massif when utilizing vertical and horizontal exchangers are analyzedin the opening part of the paper. The results of the first verification indicatedthat average temperatures in the horizontal planes of the ground massif did not differconsiderably with distance from the exchanger tube. Differences in averagetemperatures in reference and experimental lands confirmed sufficient heat potentialof the ground massif even at the peak of the heating period. The differences inaverage temperatures reached up to 6.51 K in the end of the heating period whileat the beginning of the heating period, the differences in average temperaturesdropped to 1.35 K. The differences between maximum and minimum temperaturesin the zone of the ground exchanger reached up to 1.9 K at the peak of the heatingperiod and rose to 3.9 K at the beginning and end of the heating period. The firstresults of our measurements ...
The installation of an energy-saving facility must be preceded by analysisof its financial effectiveness. Among methods enabling such evaluation is thebasic net profit calculation method. For this, the annual consumption of electricityfor ventilation or of thermal energy for heating must be determined. The calculationformula uses the sum of energies for temperatures within the range fromthe calculation temperature for the area in question to the long-term average ofthe maximum temperature at the site, or to the temperature at which the heatingpower is zero. It is necessary to know the summary time of occurrence of a giventemperature during a year. The site data can only be assessed based on long-termmeteorological information. In fact, data used by current national standards todescribe climatic conditions in the Czech Republic are from the years 1901 to1950.The dependence of the average yearly temperature on altitude is shown inFig. 1 for the 1961 1990 and 1991 2000 periods. It is evident that the averagetemperatures for the latter period are nearly 0.6 K higher than those for the formerperiod, irrespective of the altitude.In this paper the climatic conditions are assessed based on daily datameasured throughout the period from 1 January 1991 to 31 December 2000.Weather stations were ...
The objective of this paper is to zoom in on the system of separated wastecollection in Czech Republic (CR). The system of packing waste collection isdescribed. The analysis of collection of base commodities of communal waste(paper, plastics and glass) in chosen regions has been carried out. St edo eský regionhas been chosen because of the number of its inhabitants and as well becauseof its location in the middle part of CR and because it neighbours with the Czechcapital city, Prague. Region Vyso ina shows average values in base commoditiescollection. The results of the chosen regions are being compared to the presentstatus of separation of these wastes in CR which is counted by packing companyEKO-KOM. The company caries out back withdrawal and usage of wastes ofmentioned packages. ...
The article presents results of modeling and operational evaluation of specific energy consumption in four pig breeding categories, which have been realized under the project QF 3200 „Expert System for Determination Support and Optimization of Technology Processes Control in Agricultural Production“ supported by Czech Ministry of Agriculture. The first step of solution brought mathematical equations that describe physical relation of specific energy consumption to machine input, technology cycle duration, total efficiency and day time operation. As example of energy requirements of material manipulation during feeding operation, mulch treatment are presented in equations 1 to 4. Following performed analysis based on calculated and operationally proved energy consumptions were created simple mathematical equations (tab. I) that qualify relation of specific energy consumption Q [Wh∙d-1∙ks-1] to recommended or standardized values of dry pasture mkr [kg∙d-1∙ks-1], wet pasture mkr,v [kg∙d-1∙ks-1], specific mulch production mmr [kg∙d-1∙ks-1], liquid manure mk [kg∙d-1∙ks-1], stable area S1,u [m2∙ks-1], disinfected area S1,z [m2∙ks-1], technology cycle duration τTC [d] and average animal weight mz [kg-1∙ks-1]. The elementary mathematical models come out from hypothesis that individual operation and technology cycles of agricultural production is possible to optimize on the base of theoretical knowledge adjusted by real ...
This paper presents results of the verification of a heat exchanger composed of gravitation thermal pipes installed in a broiler chicken feeding facility. The objective of the study was to verify the possibility of the application of a power management system including a heat recovery system in a heavy-duty environment of a broiler chicken fattening facility and to specify effects of the system upon the specific consumption of energy for space heating and ventilation of the animal house. The calculation of the thermal balance of the animal house documents that the power management system that includes a heat recovery exchanger unit may reduce the thermal capacity of external sources of heat in the animal house by 26.5% even when subject to extreme conditions and at the atmospheric temperature of -12°C and the age of chickens being 1 day. The results of the metering and calculations of the efficiency have proven that the heat exchanger reaches the operational efficiency of 10–47% and thermal efficiency of 20–80% even during the most demanding operational first twenty days of the breeding cycle of broiler chickens. The specific consumption of energy for space heating and ventilation related to 1 kg of the live weight of ...
