Mechanical Modifications of Paraffin‐based Fuels and the Effects on Combustion Performance

Abstract

In order to enhance the mechanical properties, 6 kinds of additives of stearic acid, polyethylene wax (AÀC6A), ethylene vinyl acetate copolymer (EVA), low density polyethylene (LDPE), polypropylene (PP) and high density polyethylene (HDPE) were blended in the paraffin fuel. Mechanical properties of paraffin-based fuels were investigated by mixing 5 % in mass of different additives and increasing the mass percent of AÀC6A and LDPE. In addition, the combustion performance of the so modified paraffin-based fuels were tested by a 2D-radial burner at Nanjing University of Science and Technology. The effects of additives on regression rate were analyzed by thermal performance test (melting point and DSC) and viscosity measurement. Overall, all the additives can improve mechanical properties and the mechanical properties are enhanced by increasing mass% of additives. AÀC6A revealed the best for improving compressive strength (64.0 % increase by blending 5 mass %), LDPE revealed the best for improving tensile strength (105.3 % increase by blending 5 mass %). For combustion performance, the regression rates of paraffin-based fuels blended with stearic acid increased owing to the decreased melting points while the regression rates of the other five formulations decreased due to the increased melted liquid viscosity. The relationship between regression rate and viscosity is a power function which is not affected by additives at high temperature, thereby it is convenient to predict the regression rate by measuring viscosity.Keywords: Hybrid rocket propulsion · mechanical modified paraffin-based fuel · thermal and mechanical properties · melted liquid viscosity · regression rate [a] Y.

Innovative Methods to Enhance the Combustion Properties of Solid Fuels for Hybrid Rocket Propulsion

“…Experimental results [32] show that the presence of additives usually decreases the regression rate of paraffin-based fuels. Paraffin #58 loaded by simple blend with six different additives was investigated: stearic acid, polyethylene wax (A-C ® 6A), ethylene-vinyl-acetate (EVA), low-density polyethylene (LDPE), polypropylene (PP), and high-density polyethylene (HDPE).…”

“…The 2D-radial hybrid combustion burner ( Figure 1) was previously described [26][27][28][29][30][31][32] and is based on the original design by SPLab [33,34]. Gaseous nitrogen is used to stabilize the chamber pressure during combustion and terminate the HTPB-O 2 reaction after turning off oxygen, while compressed air is used to save nitrogen before combustion and cool off the chamber after combustion.…”

“…So far four cases were implemented; each is recalled in the following subsections. Paraffin was used as a binder: Paraffin #90 in Reference [26] and Paraffin #58 in References [27,28,32] and in this work; their main properties are shown in Table 4. .…”

“…As a matter of fact, an exponential relation was found in Reference [39] which correlates the regression rate of liquefying fuels with their liquid viscosity. Thus, the regression rate data of the tested paraffin-based fuels could be related directly to the viscosity of the corresponding liquid fuel samples and an increase in the liquid layer viscosity resulted in a decreased regression rate [32].…”

“…In this framework, a series of innovative techniques is currently under investigation at Nanjing University of Science and Technology (NUST) in order to overcome the solid fuel deficiencies so far experienced. Shen et al [26][27][28][29][30][31][32] verified new concepts such as:…”