Temperature Of Heat-transfer Agent Research Articles

FACTORS OF THE PVT-COLLECTOR EFFICIENCY FORMATION

Analytical researches of a hybrid solar collecting channel (PVT) are conducted by manufacture electric and thermal energy. The method of researches allows to analyse the following PVT-collector characteristics : a reheat temperature of an absorber and chilling liquid, as well as productivity depending on external and regime working conditions of the device. The work purpose is to work out of a method of calculation of opeating characteristics and definition of rational operating conditions of work of a hybrid solar collecting channel taking into account effective productivity. The complex mathematical model of the local analysis of processes of heat exchange and electrogeneration of a hybrid solar collecting channel for real conditions of a dynamic solar and climatic situation is used. The carried out analysis of heat exchange in alternative conditions showed that efficiency of a heat transport in a collecting channel integral cooling system ηT (a relationship of temperature of an absorber and final temperature of heat-transfer agent) is not a constant and considerably changes under the external and internal factors. It is influenced by intensity of insolation and the heat-transfer agent charge. With growth of these parametres ηT decreases. Existing dependence of electric power of a photo cell on the charge of a chilling liquid is characterised by presence of two expressed sections which are discriminated by rate of a variation of a function. The first of them, with low flux level of a liquid, differs considerable agency of functional parametres. The second one at high intensity differs asymptotic stabilisation of power. The limit values of the transition of the rate of decrease of the function correspond to the fluid flow rate of 0.08...0.085 l/(m2s). These values can be accepted for rationalisation of a refrigerating duty of the photobattery. Generalized dependences for determining the temperature of the liquid at the outlet of the device and the average temperature of the absorber are obtained. These dependences can be used to evaluate the efficiency of conversion of solar energy into electrical and thermal energy in regime optimization problems.

Possibility of Electromembrane Softening Treatment of Network Water at a Thermal Power Station

The possibility of electromembrane softening treatment of network water at a thermal power station is shown. Technology for the manufacturing of an inert anode free from noble metals or their compounds is proposed. Performed resource tests have demonstrated that such an anode can be in operation in chloride–sulfate solutions for several years almost without wear. A mathematical model describing the electrical current utilization efficiency as a function of process parameters and electrolysis regimes in the electromembrane softening of water has been developed. The results of calculating the current utilization efficiency coefficient by this model are in satisfactory agreement with experimental results. The current utilization coefficient in the formation of NaOH does not depend on the anolyte composition but appreciably decreases with increasing catholyte concentration and slightly grows with increasing current density at a constant catholyte concentration. Experiments have not disclosed any essential dependence between the specific water and CO 3 2- ion transports and the process parameters. Experiments on estimating the depth of the electromembrane softening of initial water for the heat supply networks of Kharkiv have demonstrated that the electromembrane method provides the residual hardness of 0.3–0.4 mg-equiv/dm3, which is almost four times lower than for water subjected to soda–lime treatment. The experiments performed on a test bench setup have confirmed that the application of heterogeneous cation-exchange membranes (both MK-40 (OAO Shchekinoazot) and CMI 9000 (Membrane International)) provides the possibility to attain a high current utilization ratio above 88%. The carbonate index of water after electromembrane softening corresponds to the normative requirements to water for heat supply networks with a heat transfer agent temperature below 150°C (no higher than 0.4 (mg-equiv/dm3)2]. This provides the possibility to use the treated water immediately in heat supply networks without further ion-exchange softening. Some technical and economic parameters of the softening process and the technical parameters of an industrial electromembrane softener are given, and the possibilities of the utilization of wastes and byproducts are considered.