The 2014 Formula 1 season was characterized by the return of supercharging through turbocharger in a complex hybrid propulsion system. The new direct-injection turbocompound engines V6 of 1600cc have innovative systems for the recovery of the energy otherwise wasted (Energy Recovery System-ERS). The following article introduces a one-dimensional simulation of two different engine concepts. The first one is the "split turbocharger" arrangement that allows the design of a very short "log" exhaust; the other with a traditional short-shaft turbocharger that needs a more complex and longer "tubular" exhaust. The paper demonstrates that the longer "tubular" exhaust dissipates more energy that the shorter "log" one. In this way, the efficiency is impaired and the "log" exhaust makes it possible to have more energy available to the wheels with the same amount of fuel and with the same limitation on the fuel flow. Therefore, with the current limitations in the fuel, the "log" exhaust / split-turbo arrangement is more convenient for current Formula 1 engines. In this paper, loads, pressures, power and speed of the various components of the turbocompound engine were simulated. A standard turbocharger compressor and turbine were used for the log and tubular exhaust arrangement and the results were compared. Even if the turbocharger matching is not optimal, in fact the boost pressure does not reach the maximum allowed, the comparison between the two arrangements is still valid.

Small, turbine-powered eAPUs (electric Auxiliary Power Unit) have poor off-design performance and efficiency. Turbo eAPUs remain competitive where efficiency is sacrificed to lightness and compactness. The first part of this paper summarizes the transformation of a very efficient, very large automotive turbocharger into an eAPU. A satisfactory solution for the design of the heavy fuel combustor has been found on the Giandomenico’s site. The performance of the APU is evaluated at the Garrett nominal air conditions (T0=302.6 K, p0=0.962 bar, dry air). The turbogas has an approximately linear braking torque from 50% to 100% load at nearly maximum efficiency. Below 50% load, it is more convenient to vary the maximum temperature of the cycle and adjust the generator torque. However, a better compromise can be obtained by coupling the APU with a battery that would supply the electric power under 50% load. The use of a recuperator is not convenient due to the increase in volume and the additional complication. The problem of the intake air filtering is particularly serious in dirty/sandy ground applications. Regarding efficiency, the turbogas is no match for the diesel eAPUs.

Material behavior depends on average peak temperature, stress magnitude and stress gradient. This assumption is valid since temperatures varies slowly when compared to pressure (stress). In this paper, a RR Merlin head is simulated with a few mathematical models used in Formula 1 racing. These extremely simplified models make it possible to evaluate temperatures and pressures starting from very few data. The method is described in detail, along with the many experimental coefficients available from several years of design activity. A step by step approach is used to allow the comprehension of this method that was developed by the Authors. The choice of the RR Merlin was dictated by the public availability of experimental data on temperatures. In fact, in the case of the RR Merlin XX, very reliable experimental results are available in NACA TN 2069. A reverse engineering process was applied on a rescued RR Merlin XX head. An accurate redesign was performed to obtain a 3D model. Assembly instructions and tolerances were found on original Rolls Royce overhaul manuals. In this way assembly and working loads were calculated and simulated. Nonlinear FEA analysis was performed on this CAD model with extremely satisfactory results for the thermal loads. Well known criticalities of the original design were found. The results were compared with NACA results both for heat rejection and temperatures. However, the mechanical stresses proved to be more critical for simulation and evaluation. Therefore, they will be discussed in another, dedicated paper.

The improved Mach method is ideal to evaluate the variations of turboshaft power output with temperature, altitude and humidity. With this original method, the Mach number and the density are evaluated using the equations from acoustics. In this way, simulations are extremely accurate. This paper introduces an off-design example based on a very good turbocharger that reaches a maximum pressure ratio of 5 and is equipped with a high temperature turbine. Automotive turbochargers can be converted to small turbogas generator units. The cost-effectiveness of the solution is furtherly improved by the availability of hybrid turbo-generators with the electronic-converter already included. The design details to overcome the numerous issues of the modification were detailed in the first part of this paper. The resulting unity is a very economical, compact, reliable APU (Auxiliary Power Unit). Unfortunately, the efficiency is around 10% and the improvement through a recuperator makes the APU not convenient when compared with the ones based on CRDIDs (Common Rail Direct Injection Diesel). In fact, CRDIDs have a best thermodynamic efficiency that is above 50%. The off-design performance of turbochargerderived APUs differs substantially from traditional turboshafts equipped with axial compressors and turbines. Therefore, the performance tuning requires a different approach.

This study aims to realize continuous, high efficiency defrosting of air-to-air heat pumps using the effect of outdoor warm air recycling, trying to improve the coefficient of performance (COP) and total heat capacity of traditional defrosting methods like hot bypass and Joule heating. The proposed patented method recovers heat from the air change system by mixing the warm discarded air with the incoming air of the external heat exchanger. The fan of the external unit sucks the indoor air with the depression obtained by a Venturi. The warm air is ducted to the Venturi through a hole in the wall. The amount of warm air mixed to the outside air is regulated by a butterfly valve installed on the pipe from the hole to the Venturi. In this way, the air entering the external coil is warm enough to avoid frost. The energy efficiency of the system is assured, for the warm indoor air is heated with the high COP of the heat pump. Our system can achieve defrosting with a limited amount of warm air, and realize a higher overall COP than the best traditional defrosting systems. Finally, the defrosting device can be added as an option to any existing split systems.