Performance Assessment of Thermoelectric Generators with Application on Aerodynamic Heat Recovery

Based on thermoelectric generators (TEGs), an aerodynamic heat energy recovery system for vehicle is proposed. A mathematical model describing the energy conversion law of the system is established, and the integrated calculation method which combined aerodynamic heating and thermoelectric (TE) conversion is given. Furthermore, the influences of the typical flight Mach number, flight altitudes and the length of TE legs on the energy conversion behavior of energy recovery systems are investigated. The performance of the energy recovery system is analyzed and evaluated. The results show that, the decrease of flight altitude and the increase of Mach number will obviously improve the performance of the heat energy recovery system with TEGs. The increase of leg length will increase the temperature of the hot end of TEGs and reduce the heat absorbed at the hot end. When the external load, Mach number and flight altitude is fixed, there exists an optimal length of legs corresponding to the maximum output power and maximum conversion efficiency of the system. The results will have significant positive impact on thermal protection and management of supersonic / hypersonic vehicles.

The Subcooling Effect of the Flue Gas Flow Mixture Internal Dynamic and Heating Capacity

Growing environmental restrictions in energy production industry calls for greater efficiency and cleaner fuel burning processes. Biomass (wood chips) as a fuel is in great demand for boiler and power plants as it is considered widely available and relatively clean. While combining woodfuel flue gas and condensing economizers significantly raises the efficiency and makes it even more viable solution for energy production although the biomass fuel usage still has reservations in waste heat, which could be utilized. The calculation algorithm is presented for evaluation of subcooled biomass flue gas components concentration values which determine the leftover heat energy value carried by flue gas flow. Several cases of biomass quality (regarding moisture w=45%, 50%, 55% and 60%) and combustion process quality (regarding air excess value λ=1,2; 1,5; 1,8) in the flue gas temperature range of 50 to 20°C and effects for flue gas internal dynamic were examined. It was determined that water vapour amount depends only on temperature, while every other component concentration change with different air excess and temperature values. It was observed that further usage of biomass flue gas could result in up to 13% additional heat energy recovery for 1MW of fuel input, system combination together with condensing economizers could result in up to 31% of heat energy recovery.

Automobile based heat energy recovery systems

In today's world, energy-saving and waste energy recovery are an important aspect, and it is more critical in the automotive sector. This is mainly due to vehicles are running on fossil fuel. This paper presents review on state of art waste energy recovery systems for automobiles. With further development, this system has the potential in deployment in many other industries. This technology can also be used to store electrical energy which will further be helpful in both hybrid and electric vehicles.

Comparison of Heat Recovery Ventilator Frost Control Techniques in the Canadian Arctic: Preheat and Recirculation

Air-to-air heat/energy recovery ventilators can effectively reduce the cost associated with ventilating a home. However, high indoor moisture levels, in conjunction with extreme temperature differences between the outdoor and indoor air can cause frost accumulation in the mechanical equipment, leading to performance degradation or failure. In this research, a demonstration house using a heat recovery ventilation system in Iqaluit, Nunavut, Canada was used to compare the performance of two frost control techniques: recirculation and electrical preheat. The advantages and disadvantages of each method are outlined to highlight the need to adapt southern strategies to ensure system functionality in the Arctic. The system was equipped with a heat recovery ventilator (HRV) with built-in recirculation technology to defrost the HRV, as well as two electric preheaters that can be used instead of recirculation and prevent frost formation. Between December 2018 and April 2019 the ventilation system’s performance was monitored for seven weeks while using either recirculation or electrical preheat. The experiments showed the ventilation system equipment consumed more absolute energy with electrical preheat than with recirculation as the frost control technique. However, when using recirculation, the ventilation system experienced more losses throughout the ventilation system, causing the whole building to consume more energy due to an increase in energy consumption by the home’s heating system. Moreover, the quantity of outdoor air that was restricted while using recirculation made electrical preheat the superior option for this ventilation system design. The energy use of the ventilation system with electric preheat enabled was 35% lower on a per volume of outdoor air basis. Contrary to some belief that preheating is a poor approach for frost control in heat/energy recovery ventilators, this research finds that preheating can be a more energy efficient method to provide ventilation if controlled well.

Thermochemical conversion of plant biomass in the energotechnological complex with heat recovery

Basic performance principles of the energotechnological complex used for thermochemical conversion of plant biomass with the influence of a magnetic field and high recovery of spent heat carrier energy have been developed. The concurrent saturation of a spent heat carrier in a loading bunker with the steam from humid biomass aimed at using a certain part of a spent heat carrier, which is clear from oxygen and nitrogen oxide, and moisture in thermochemical recovery has been considered as an important aspect of recuperation processes. A mathematical model has been developed and the results of numerical simulation have been presented for determining the distribution of temperature, velocity and pressure fields in a loading bunker. Prospective assessment of the engineering solutions developed for heat energy recovery of a double-flow spent heat carrier has been conducted.