The present invention relates to an improved system for conversion of energy, especially the available energy in natural gas, and is also concerned with an improved form of power package and components thereof, particularly adapted to be used in the improved energy conversion system. 
In prior systems for distributing and converting the energy of natural fuels, such as natural gas, it is known to burn the gas in central power plants for the purpose of generating electricity, and the electricity is then distributed through transmission lines to various points of use where the electrical current is employed to drive a wide variety of devices such as motors for developing mechanical power or torque for use in operating machinery or for driving compressors, pumps and the like, and such electrical current is also employed for heating purposes both for industrial operations or for comfort heating and other purposes.  As is well known, such prior known energy conversion and distribution systems are highly inefficient, since the ultimate consumer actually receives less than about 25% of the available energy in the gas initially burned to generate the electrical current, the remaining energy representing losses of available BTU value in the central power plant where the fuel is burned, in the transmission lines for the electrical current, in transformer losses and other miscellaneous points of inefficient conversion of the energy from one form to another. 
Such losses are rapidly becoming intolerable having in mind the dwindling supplies of fuel.  With this situation in mind, it has already been proposed to increase the efficiency of burning of various of fuels, particularly natural or other combustable gas, but at best, the attempts in this direction have not resulted in more than about 40% efficiency.  In consequence, for most purposes, it is not presently practicable to effect a changeover on a large scale, from power distribution by electrical transmission lines, to power distribution by natural gas transmission lines. 
One of the major objectives of the present invention is to provide power or power plant packages adapted to many commercial, industrial and even domestic uses, and which are of such high efficiency with respect to energy conversion that it becomes practicable to employ an energy conversion and power distribution system in which natural gas may be distributed through transmission lines to a multiplicity of points of use or local power stations, at each of which a power package is provided not only capable of high efficiency in energy conversion, but also of such character as to be readily adaptable to the varying power needs of different commercial, industrial and domestic uses. 
Having in mind that the fuel with which the system and components thereof are especially adapted for use, for instance natural gas, is a fuel which, upon combustion, yields an exhaust gas containing substantial quantities of water vapor, it is contemplated according to the present invention to provide a power package to be employed at the various points to which the gas is distributed, which power package includes not only a combustion engine but further includes means for developing a supply of hot water from the heat available in the engine jacket water and/or the exhaust gases. 
According to the invention a heat exchanger is employed, of special form several embodiments of which are described hereinafter, in which the engine exhaust gases and a supply of water are brought into heat exchange relation in a manner to bring the exhaust gases and thus the water vapor carried thereby down to a temperature below the dew point, in consequence of which the invention provides for the utilization of the heat of condensation for the purpose of heating the water to be employed in the establishment of the hot water supply.  Although the heat exchangers herein disclosed are especially well adapted to the purpose just referred to, the disclosed heat exchangers are also highly efficient for other purposes as will be pointed out more fully hereinafter. 
Additionally it is contemplated according to the present invention that the engine in which the gas is burned be connected to drive an electric generator in order to supply the requirements for electricity at the point of installation of the power package, or to drive a refrigeration compressor, or other machinery, whatever the need may be. 
In addition it is contemplated, according to one embodiment to employ an engine cooling means of a type adapted to establish a source of supply of steam at a pressure appropriate for various uses where the power packages are installed. 
By the utilization of a power package of the kind referred to above and more fully described hereinafter, the invention provides a capability of recovering and using as much as 85-90% of the available energy of the fuel consumed. 
Certain of the heat exchangers disclosed are advantageously used in order to establish a supply of hot water by recovery of heat from the exhaust gas of the engine.  The heat exchangers herein disclosed for this purpose embody a number of improvements which not only make practical high efficiency in the recovery of heat from the engine exhaust or products of combustion but which also result in improved operation and extended life of the equipment, particularly from the standpoint of reduction in deterioration under the corrosive influences of components of the products of combustion as will be further explained. 
Various of the heat exchangers disclosed may be used for a variety of purposes not necessarily associated with power packages of the kind herein disclosed; and in one disclosed embodiment the heat exchanger incorporates a combustion chamber in novel interrelation to other components of the exchanger, as will be pointed out more fully hereinafter.