In this paper two alternative solar methods are evaluated for the methane generating system using the municipal solid waste, MSW in urban zones. The analytic method evaluates the use of flat solar collector; in one case they are remaining fixed and the other case they have a solar tracking system. The analytic results shown that the needs of conventional energy to the generation biogas system were minors using the solar tracking system

This paper presents results given by a waste heat recovery (WHR) system applied to a highperformance video card, as well as average energy generated per hour according to emulation of computer graphics requirements demanded by the user while the card is working. A WHR system includes three phases: (1) waste heat collection, (2) energy conversion and (3) signal conditioning. The analysis of the WHR system is presented. The emulation of waste heat has been generated using electrical resistors as if they were the main components that generate waste heat, mainly the GPU (graphics processing unit), and DDR3 memories. This WHR system has considered the MSI-R4850 video card as a reference, operation temperature of which has an overall range between 60°C – 90°C. Thermoelectric generator modules (TEG) are based on the Seebeck effect, and the thermoelectric array used is an important part of the WHR system, which has been constructed based on the locations of the main components to convert waste heat into electrical power. The waste heat recovery process has two treatments: First, once the operating conditions, per GPU and DDR3 memories have been emulated, the energy recovered is measured per component and whole WHR system; the second one measures energy recovered considering the output signal conditioning of the WHR system, which was converted to 5V output through a DC-DC boost converter, while the input voltage operates within a range (0.9V – 5V). The energy recovered may be applied to low-power electronic devices, which is a contribution to energy efficiency.

It is shown a mathematical model of a solar box cooker with multi-step inner reflector and the numerical results for two applications has been analyzed. These applications are 1. Numerical simulation of operation of solar box cooker with multi-step inner reflector in Tanta, Egypt and 2. Numerical simulation of solar box cooker with multi-step inner reflector for 10 hours of operation. In the case 1, is analyzed a solar box cooker constructed and evaluated in Tanta, Egypt [1]. The experimental results that was obtained are compared with the numerical results that was obtained for the mathematical model. The case 2, is an evaluation of numerical results that was obtained for the operation of 10 hours for solar box cooker constructed in the Laboratorio de Ingenieri´a Te´rmica e Hidra´ulica Aplicada (LABINTHAP) in Me´xico City. [4] The solar box cooker is integrated by a covert that was made with double glass, this is use with two purposes, reduce the loss heat convection with outer and to generated the greenhouse effect with inner of cooker. In the inner of cooker there are a mirrors arrangement in inclined position (inner reflectors) placed in angles of 30°, 45° and 75°, these helped to reflex the solar rays in direction to the cook recipient. The recipient also received the solar rays in the upper part (lid). The mathematical model that was obtained from energetic analysis, is formed for five differential equations system no linear and the fourth Runge-Kutta method is used to resolve it. The numerical solution of the equations system is obtained with a computational software in C++. This work is a contribution to the application of numerical methods and computational for development of the solar energy used in thermal conversion equipments. The use of these techniques to solve the mathematical model is important to contribute in the evaluation and design of solar box cookers with multi-step inner reflector.