Аpproximate method for the estimation of energy performance of heat pumps connected to the system of energy management of facilities

Due to their efficiency heat pumps have found great application in the building industry, the process industry, in various technological processes in the production of food, to the space technology system, etc. When heat pumps are coupled to the energy management system which monitors and optimizes work parameters not only of the heat pump but also work parameters of other systems, such as solar and photovoltaic panels, thermal energy storages, electric batteries and the whole system, it is necessary to have a mathematical model that with sufficient accuracy and without great complexity estimates energy performance of the heat pump itself and the whole energy system. In this article a relatively simple mathematical model of a heat pump, with which it is possible to get values for the COP at any given time and under given conditions, was given. The obtained results of the model, applied to the air-water heat pump, used the input meteorological data of the mean air temperature for Belgrade, were presented. The verification of the obtained results of the model was made by using the catalogue data for the COP of the the Ecodan Monobloc Air Source Heat Pumps manufactured by Mitsubishi Electric

Reduction of carbon monoxide emission from a solid-fuel thermo-accumulation furnace

Many households in Serbia, using electric thermo-accumulation furnaces for heating, have been forced to find an alternative solution, due to a significant increase in electricity prices during the last decade. A possible solution is replacing electric heating appliances with the solid fuel-fired ones. A prototype of a new concept of thermo-accumulation solid fuel-fired furnace has been developed to meet these growing needs, providing electricity saving together with considerable environmental benefits. Two strategies for reduction of carbon monoxide emission are examined in the paper: application of Pt/Al2O3 catalyst, in the form of 3 ± 0.3 mm spheres, providing further combustion of flue gases within the furnace, as well as an additional emission reduction by means of the air excess control. Experimental investigations of the catalyst influence on the conversion of carbon monoxide have been done for different operation regimes and positions of the catalyst. The paper presents selected results regarding carbon monoxide emission during wood and coal combustion. Investigations suggest a considerable effect of the catalyst and a strong influence of the catalyst position within the furnace to carbon monoxide emission reduction. In addition, experimental tests have been conducted to asses the effect of the air excess control in the furnace on carbon monoxide emission. The amount of combustion air, the flue gas flow rate, and the fuel feeding regime have been adjusted in order to keep the flue gas oxygen content in a relatively narrow range, thus obtaining controlled combustion conditions and lower carbon monoxide emission. In this way, the furnace has been made able to respond to the changes in heating needs, fuel quality and other parameters, which is advantageous in comparison with similar solid-fuel fired furnaces

Vertical temperature profile in the fluidized bed installation for combustion of waste fuels

Ovaj rad je prilog istraživanju sagorevanja čvrstih i tečnih otpadnih goriva. U tečna otpadna goriva čije odlaganje predstavlja ekološki problem ubrajamo talog iz rezervoara sirove nafte kao i korišćena jestiva/mineralna ulja i glicerin kao nus-produkt proizvodnje biodizela. Pored toga, ove materije, zbog neujednačenog sastava i gustine kao i visokog udela balasta, se ne mogu sagorevati u konvencionalnim ložištima, pa je tehnologija pogodna za njihovu toplotnu dezintegraciju fluidizovani sloj jer omogućava sagorevanje najrazličitijih vrsta goriva neuniformnog sastava. U čvrsta otpadna goriva ubrajamo i vanbilansne rezerve uglja (sitne granulacije, sa visokim sadržajem mineralnih materija i niskom toplotnom moći) koje je potrebno koristiti racionalnije, što opet podrazumeva primenu ložišta sa fluidizovanim slojem. U kotlovima sa fluidizovanim slojem mogu se sagorevati čvrsta goriva sa 85% inertnih materija, sa efikasnim odsumporavanjem dodavanjem krečnjaka direktno u ložište, sa niskom emisijom NOx, što ovoj tehnologiji daje značajnu prednost u poređenju sa drugim tehnologijama sagorevanja. U radu je dat opis eksperimentalne instalacije, kao i rezultat eksperimenata, sa naglaskom na raspodelu temperature po visini ložišta, u cilju određivanja zone intenzivnog sagorevanja u zavisnosti od karakteristika goriva.This paper is a contribution to the investigation of combustion of waste liquid and solid fuels. Waste liquid fuels include sediment from crude-fuel oil tanks or used edible/mineral oils, the disposal of which is most of ten linked to environmental issues. In addition, these substances, due to high ballast content, non-uniform composition and density, can not be burnt in conventional combustors, hence the technology of thermal disintegration in the fluidized bed (FB) imposes as a solution, which enables the combustion of fuels of most distinct types and non-uniform compositions. Waste solid fuels refer to coals from off-balance reserves (fine-grained, with high ballast and sulfur contents and low heating values) which should be used more rationally, implying the application of the FB combustion (FBC) as well. The fact that FB boilers can burn fuels with 85% of inert materials, with effective retention of SO2 by adding lime stone into the furnace, and with lower NOx emissions, gives FBC significant advantages, compared to other combustion technologies. Description of the experimental FBC facility is given, as well as experimental results, with the focus on the furnace temperature distribution, in order to determine the location of the intensive combustion zone as a function of fuel properties.

Results of combustion of different waste fuel in fluidized bad

Održivi razvoj domaće energetike podrazumeva racionalno korišćenje energetskih resursa, upotrebu obnovljivih izvora energije i upravljanje otpadom uz zadovoljenje ekoloških propisa. Način za istovremeno ispunjavanje navedenih ciljeva je energetsko iskorišćenje niskovrednih, otpadnih materija, primenom tehnologije sagorevanja u fluidizovanom sloju (FS). U radu su prikazani rezultati eksperimenata sagorevanja više vrsta čvrstih i tečnih otpadnih materija, obavljeni na dvema instalacijama: industrijsko-demonstracionom (snage do 500 kW) i eksperimentalnom FS kotlu (snage do 100 kW). Mereno je temperatursko polje po visini ložišta, analiziran sastav dimnih gasova na izlazu iz ložišta i ostali parametri sagorevanja predmetnih goriva. Analizom dobijenih rezultata data je ocena njihove podobnosti sagorevanja u FS uz mogućnost iskorišćenja njihovog energetskog potencijala.The sustainable development of the national energy sector implies the rational use of energy resources, use of RES, and waste management with satisfying environmental regulations. A way to simultaneously fulfill the above objectives is the utilization of low-calorific and waste materials, applying the technology of fluidized bed combustion (FBC). This paper presents experimental results of combustion of number of solid and liquid wastes, conducted on two installations: industrial demonstration (capacity up to 100 kW) and experimental FB boiler (capacity up to 500 kW). The furnace temperature distribution, the composition of flue gas at the exit of furnace, and the other combustion parameters of the fuels are given. On the basis of these results, an evaluation of the waste fuels FB combustion and possibility of utilization of their energy potential is given

Results of combustion of different waste fuel in fluidized bad

Održivi razvoj domaće energetike podrazumeva racionalno korišćenje energetskih resursa, upotrebu obnovljivih izvora energije i upravljanje otpadom uz zadovoljenje ekoloških propisa. Način za istovremeno ispunjavanje navedenih ciljeva je energetsko iskorišćenje niskovrednih, otpadnih materija, primenom tehnologije sagorevanja u fluidizovanom sloju (FS). U radu su prikazani rezultati eksperimenata sagorevanja više vrsta čvrstih i tečnih otpadnih materija, obavljeni na dvema instalacijama: industrijsko-demonstracionom (snage do 500 kW) i eksperimentalnom FS kotlu (snage do 100 kW). Mereno je temperatursko polje po visini ložišta, analiziran sastav dimnih gasova na izlazu iz ložišta i ostali parametri sagorevanja predmetnih goriva. Analizom dobijenih rezultata data je ocena njihove podobnosti sagorevanja u FS uz mogućnost iskorišćenja njihovog energetskog potencijala.The sustainable development of the national energy sector implies the rational use of energy resources, use of RES, and waste management with satisfying environmental regulations. A way to simultaneously fulfill the above objectives is the utilization of low-calorific and waste materials, applying the technology of fluidized bed combustion (FBC). This paper presents experimental results of combustion of number of solid and liquid wastes, conducted on two installations: industrial demonstration (capacity up to 100 kW) and experimental FB boiler (capacity up to 500 kW). The furnace temperature distribution, the composition of flue gas at the exit of furnace, and the other combustion parameters of the fuels are given. On the basis of these results, an evaluation of the waste fuels FB combustion and possibility of utilization of their energy potential is given

Three phase eulerian-granular model applied on numerical simulation of non-conventional liquid fuels combustion in a bubbling fluidized bed

The paper presents a 2-D CFD model of liquid fuel combustion in bubbling fluidized bed. The numerical procedure is based on the two-fluid Euler-Euler approach, where the velocity field of the gas and particles are modeled in analogy to the kinetic gas theory. The model is taking into account also the third liquid phase, as well as its interaction with the solid and gas phase. The proposed numerical model comprise energy equations for all three phases, as well as the transport equations of chemical components with source terms originated from the component conversion. In the frame of the proposed model, user sub-models were developed for heterogenic fluidized bed combustion of liquid fuels, with or without water. The results of the calculation were compared with experiments on a pilot-facility (power up to 100 kW), combusting, among other fuels, oil. The temperature profiles along the combustion chamber were compared for the two basic cases: combustion with or without water. On the basis of numerical experiments, influence of the fluid-dynamic characteristics of the fluidized bed on the combustion efficiency was analyzed, as well as the influence of the fuel characteristics (reactivity, water content) on the intensive combustion zone

The heat and mass transfer in a large lignite coal particle devolatilizing in FB

A theoretical study has been performed in order to investigate heat and mass transfer processes in a lignite particle during the devolatilization. A mathematical model, describing the devolatilization process, has included the internal and external heat transfer, primary decomposition reactions and mass transfer. The input of the numerical model has been: coal thermal properties, chemical kinetic parameters, particle diameter, volatile matter amount, and fluidized bed temperature. The output includes: the temperature, the amount of volatiles released, the rate of devolatilization, volatile matter flux, and the pressure inside the particle. The model enable closer insight of transfer processes within the lignite particle, devolatilizing in FB, and shows how the FB temperature and original size of coal reflect on the pressure profile of the lignite particle, devolatilizing in FB