Influence of the pressure fluctuations on the temperature in pad/disc tribosystem

The influence of the duration of increase in pressure from zero (at the initial moment of time) to nominal value (at the moment of a stop) on the temperature for a friction pair metal–ceramic pad/cast iron disc is studied. Fluctuations of pressure are taken into account, too. The analytical solution to a thermal problem of friction during braking is obtained for a plane-parallel strip/semi-space tribosystem with a time-dependence friction power and the heat transfer through a contact surface.     

Investigation of the temperature field induced in the process of friction of a composite pad and a homogeneous disc

The analytical model for the determination of transient temperature field and heat fluxes in friction elements of brakes (pad/disc) is presented. It is assumed that one friction element is composed of a multi-layer composite strip, and the second element is a homogeneous semi-space. The solution to a non-stationary thermal problem of friction is obtained for a tribosystem with heat generation on a surface of contact and convective heat exchange with an environment on outer surface of a strip. The influences of composite parameters, for example, reinforcement fraction in the cross-section of periodic cells and the ratio of the conductivities of matrix and fibers, on the maximal temperature are studied.     

Experimental investigation of temperature and flow distribution in a thermosyphon solar water heating system

Natural circulation solar water heating systems are available in varying collector geometries (and materials), storage tank capacities and specifications of individual components. Though theoretical and experimental studies including the test procedures are available to estimate the performances of these systems, detailed experimental studies showing the temperature profiles of the absorber plate, water temperature in the riser and water flow in the riser are few. This paper presents details of experimental observations of temperature and flow distribution in a natural circulation solar water heating system and its comparison with the theoretical models. The measured profile of the absorber temperature near the riser tubes (near the bottom and top headers) conforms well with the theoretical models. The values at the riser tubes near the collector inlet are found to be generally much higher than those at the other risers on a clear day, while on cloudy days, these temperatures are uniform. The mean absorber plate and mean fluid temperature during a day has been estimated and compared with theoretical models. The temperature of water near the riser outlets was found to be fairly uniform especially in cloudy and partly cloudy days at a given plane during a day. The temperature of water in the riser depends on its flow rate. Measurements of glass temperature were also carried out.