Thermal Performance Optimization And Economic Analysis Of A New Type Of Steel Special-shaped Tube Radiator

In order to optimize a new type of special-shaped steel tube radiator,this paper makes a detailed analysis about the development history,industry status,theoretical calculation,experimental test and data simulation of the steel radiator,confirming that the research on this kind of radiator has social and economic benefits.In the introduction,the development and current situation of radiator heating industry are introduced.By comparing and analyzing various kinds of tubes and tube shapes,it is confirmed that the design of new type of steel shaped tube radiatorconforms to the current"Code for Energy Saving Design of Residential Buildings"in China.It is pointed out that the shape and size of the radiator’s special-shaped single tube have great influence on the forced convection heat transfer coefficient in the tube and the natural convection heat transfer coefficient in the outer surface,but the influence on the actual heat dissipation is neglected in the calculation of the single management theory.Therefore,in this paper,the double-cylinder shaped tube radiator is taken as the research object,and the convective heat transfer outside the tube is divided into the transverse coordinate heat transfer and the natural convective heat transfer in the ordinate coordinate by the way of sub-coordinate.According to the analysis,the dimension of single tube is still the main factor affecting the heat transfer of the radiator under the limited conditions.Therefore,a new Nusselt calculation method of laminar heat transfer around a special-shaped tube bundle is proposed based on the laminar heat transfer of an outer-swept tube:Nu_x=C×Re_fⁿ×Pr^1/3×（1+（s/b））^m1×（1+（a/b））^k1.In the process of testing,a group of samples were tested several times according to the national standards and the corresponding testing methods,and the data were sorted out and summarized,and the heat transfer relationship between the radiator heat dissipation and the water temperature difference between the inlet and outlet was obtained.As the research object,the radiator heat dissipation and metal heat intensity are simulated by ANSYS software,and a set of radiator test values and their corresponding ANSYS simulation values are compared and analyzed in this paper.In other simulations,the correction coefficients in the theoretical calculation are linearly induced by the equivalence between the corrected simulated values and the calculated values of the numerical theory,and the empirical formula of Nusselt number for the special-shaped tube bundles is obtained under the limited conditions.This formula has some limitations in theoretical calculation.The main reasons are as follows:Firstly,the formula is based on laminar heat transfer of air-swept circular tubes,which is suitable for the shapes of quasi-circular tubes and elliptical tubes.When the length-width ratio of a single cylinder is large,the error is large.Secondly,the formula is deduced under the condition of confining the section circumference,column spacing and row spacing of a single radiator tube,and its applicability is narrow.In this paper,the heat dissipation and metal thermal strength of different sizes of radiators are obtained by numerical calculation and simulation analysis.The results show that:1.When the aspect ratio of a new type of special-shaped steel tube radiator is in the range of[1.199,4.345],the heat dissipation increases first and then decreases with the increase of aspect ratio of the single tube;The standard range is[2.9317,3.355];2.The metal thermal strength of the new type of steel shaped tube radiator increases first and then decreases in the range of single tube aspect ratio[1.199,4.345],and the peak range of metal thermal strength is[3.5374,3.9412];the change trend of metal thermal strength when the aspect ratio is in the range[3.9412,4.345]is more than that of single tube section[1.19].The trend of change at 9,3.9412 is somewhat gentle.3.The change of metal heat intensity and heat dissipation of the new type of special-shaped steel tube radiator is not synchronous,and the peak value corresponds to different abscissa.The conclusions obtained in this paper have a certain guiding significance for the optimal design of radiator,and also have a certain reference significance for engineering calculation.