41. On houses they serve as a retrofit on existing windows in order to improve their thermal efficiencies . 42. This reference states that a 20 % to 30 % increase in engine thermal efficiency is possible. 43. Thus an excessively high ratio can lead to a decreased thermal efficiency compared to other engine geometries. 44. By the time this was achieved the thermal efficiency gains were lost, and the experiment was abandoned. 45. Overall thermal efficiency is 60 %. 46. This prevents the ash from building up and sintering onto the boiler tubes thus significantly reducing thermal efficiency . 47. Further improvements in core thermal efficiency can be achieved by raising the overall pressure ratio of the core. 48. This condition allows higher thermal efficiency . 49. To reduce fuel costs the thermal efficiency of both types of engine have been improved over the years. 50. The latest technologies in Formula One engines have seen a boost in thermal efficiency to almost 47 %.
