HEAT ENGINE

Abstract: This heat-activated refrigeration system couples a heat pump (21) to a rotary fluid motor (18) and starting means (41b). The heat pump cycle maintains the system in thermal equilibrium by replacing energy leaving a regenerative refrigerant cycle. A shaft (19a) from the rotary fluid motor (18) drives the compressor (11). The compressor (11) discharge line (13) branches so that one line (14a) couples to the rotary fluid motor (18) to drive it, while the other line (14b) delivers refrigerant to a heat pump (21). Return flow from the fluid motor (18) and return flow from the heat pump (21) converge at the compressor suction line (12). The system can function as a heat engine with a power take-off shaft, (19b) or it can function as an ambient heat-activated refrigeration system, depending upon the size of its system components.

Description: FIELD OF THE INVENTION The invention involves two refrigerant cycles which are used in ambient heat-activated refrigeration systems and in engines which use ambient heat for their energy input. BACKGROUND OF THE INVENTION Refrigeration systems absorb ambient heat in the area of their evaporator and they release heat in the area of their condenser. Heat-activated refrigeration systems differ from vapor-compression refrigeration systems in that their com¬ pressors are driven by refrigerant turbines, or the like. To activate the turbine, the refrigerant absorbs thermal energy wholly or partially from an external source. Prior art recognizes that excess energy to the compressor could be used at a power take-off shaft. Examples of heat-activated refrigeration systems are taught by United States Patent Nos. 2,486,034, 2,511,716, 2,737,031, 3,172,270 and 3,400,555. SUMMARY OF THE INVENTION The invention consists of a heat-activated refrigera¬ tion system with an improved method of heat energy conversion. The method incorporates a regenerative refrigerant cycle and a heat exchanger in the system so as to retain most of the system's working fluid in its superheated gaseous state. Otherwise, thermal energy would be wasted by allowing all of the refrigerant to condense from a vapor into a liquid in the condenser. The heat pump subsystem absorbs ambient heat energy at the evaporator. This is used to compensate for thermal energy losses in the regenerative refrigerant cycle as thermal energy is converted into shaft-work. The invention can serve either as an ambient heat- activated refrigeration system, or as a heat engine, depending upon the sizing of its components. It will hereafter be disclosed in its heat engine context. * The engine is started by shutting off the by-pass valve between the high-pressure side and the low-pressure side of the system. Then the starter compressor motor is started up, so as to develop a pressure difference within the system. Forces acting within the fluid motor are then converted into shaft-work. The engine is stopped by opening the by-pass valve so as to equalize pressures throughout the engine. A capacity control valve in the compressor adjusts the engine speed by varying the amount of fluid which flows through the positive displacement fluid motor. In very cold weather the engine is energized by routing thermal energy to the evaporator from an auxiliary heat source. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic diagram of the heat- activated refrigeration system showing the inven¬ tion in a heat engine. Fig. 2 is a pressure-enthalpy diagram for a Freon refrigerant, showing the system's heat pump cycle. Fig. 3 is a pressure-enthalpy diagram for a Freon refrigerant, showing the system:'s regenera¬ tive cycle. DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to Fig. 1 of the drawings, the heat engine includes a fluid compressor 11 with an inlet line 12 and a discharge line 13. Discharge line 13 branches into lines 14a and 14b. Line 14a couples to fluid motor 18. Line 14b couples through a restrictor 16 to heat exchanger inlet line 15. Fluid flow through motor 18 causes the rotation of shafts 19a and 19b. Compressor 11 is driven by shaft 19a while work is coup- led from power take-off shaft 19b, which can extend from either motor 18 oϊ compressor 11. The outlet port of motor 18 couples to the compressor inlet port through lines 20a and 12. Capacity control yalve 11a in compressor 11 is used to adjust the engine shaft speed. Liquid refrigerant evaporates and absorbs thermal energy when it flows through evaporator 25. Then the flow is mixed in lines 20a and 12 with superheated refrigerant re¬ turning from fluid motor 18. Heat exchanger 26 also trans¬ fers thermal energy from heat exchanger inlet 15 to refrig¬ erant in compressor inlet 20a. These heat transfers com¬ pensate for thermal energy losses and maintain the system in thermal equilibrium. Refrigerant vapor dissipates thermal energy when it flows through condenser 22. It cools down to its liquid state and is held in liquid receiver 23 until re¬ quired. Then the refrigerant passes through dryer 24 so that any moisture is removed from it. Thermostatic expansion valve 27 regulates the amount of refrigerant flow through evapora¬ tor 25 to meet changing load conditions. Arrowheads show the direction of refrigerant flow in lines 31, 32, 33, 34 and 35. The heat engine stops when by-pass valve 46 is open- ed and system pressures are equalized. To re-start the en¬ gine, by-pass valve 46 is closed, shutting off high-pressure line 45 from low-pressure line 47. Then starter motor 41b drives starter compressor 41 until the pressure differential is reached and check valve 44 closes. Only the heat engine version of the invention has power take-off shaft 19b. Figs. 2 and 3 show pressure-enthalpy diagrams for the two refrigerant cycles. Refrigerants like R-13B1 are marketed by the Du Pont Company under the tradename of FREON. The term "Freon" will be used for the working fluid in the heat-activated refrigeration system and the heat engine. Fig. 2 shows changes taking place in the Freon during the heat pump cycle by means of a pressure-enthalpy diagram. The Freon expands when it passes through expansion valve 27, as line 102 indicates. Line 103 indicates that heat is absorbed by Freon to state-point 104 at compressor inlet line 12. The heat of compression is added to the Freon along line 105 until it reaches state-point 106 at the compressor discharge. Com¬ pressor discharge line 13 branches so that some Freon goes to drive fluid motor 18 and the rest returns to the heat pump cycle. Some of the Freon*s heat is converted to shaft-work as it passes through fluid motor 18. Freon going to the heat pump cycle passes through heat exchanger 26 which transfers some of its heat to the regenerative cycle before it liqui- fies in condenser 22 to state-point 101. Fig. 3 is a pressure-enthalpy diagram for Freon in the regenerative refrigerant cycle. Thermal energy from the heat exchanger and the heat pump make up for thermal energy converted to shaft-work so that Freon expands from state- point 108a to state-point 108b along line 109. Expansion occurs in compressor inlet lines 20a and 12, while compressor discharge flows through lines 13, 14a and 14b. Having described the preferred embodiment of my invention, one skilled in the art, after studying the above description of my preferred embodiment, could devise other embodiments without departing from the spirit of my invention. Therefore, my invention is not to be considered as limited to the disclosed embodiment, but includes all embodiments fall¬ ing within the scope of the appended claims.

Claims: : 1. A heat-activated refrigeration system for performing shaft-work comprising: a rotary fluid motor or other positive displace¬ ment expander, having an inlet for a refrigerant gas and an 5 outlet for said fluid, permitting work to be obtained from # said rotary fluid motor at a power take-off shaft; a refrigerant compression means having an inlet for said refrigerant, an outlet for said refrigerant and a rotatably mounted shaft by which said compressor may be driven; 10 connecting means between said shaft of said com¬ pressor and said shaft of said rotary fluid motor by which said compressor is driven by said rotary fluid motor; heat pump means to absorb heat from an ambient source a refrigerant flowing through said heat pump, said 15 compressor and said rotary fluid motor; connecting means by which heat flow from said heat pump and the outlet of said rotary fluid motor are connected to the inlet of said compressor; and connecting means by which the inlet of said heat 20 pump and the inlet port of said fluid motor are connected to the discharge port of said compressor whereby the flow rate of said refrigerant is regulated. 2. A heat engine as in Claim 1 wherein said heat engine further comprises an engine stopping means consisting of a by-pass valve between the high-pressure side and the low- pressure side of the system. 3 . A heat engine as in Claim 1 which further com¬ prises: an engine starting means consisting of an auxiliary refrigerant compressor means with the discharge port of said compressor connected to the inlet of check valve, said check valve preventing flow of fluid into said outlet; and said starting means being connected between the high- pressure side and the low-pressure side of the system. 4. A heat engine as in Claim 1 which further com¬ prises heat exchanger means between refrigerant flow to the heat pump and refrigerant flow to the compressor inlet port. 5. A heat engine as in Claim 1 which further com¬ prises restriction means between the outlet of said compres¬ sor means and the inlet of said heat pump condenser means. 6. A heat engine as in Claim 1 which further com¬ prises control means for varying the speed of operaticnof said fluid driven motor. 7. A heat engine as in Claim 6 in which said con¬ trol means comprises flow regulation means in the compressor for said refrigerant. 8. A heat engine as in Claim 1 which further com¬ prises two refrigerant cycles, consisting of a heat pump cycle and a regenerative refrigerant cycle. 9. A heat-activated refrigeration system as in Claim 1 wherein said refrigeration system is used to remove heat from a closed area or supply heat to a closed area.

Inventors: JEPSEN HENRY E, JEPSEN, HENRY, E.
Applicants: JEPSEN HENRY E, JEPSEN, HENRY, E.
Application year: 1983
Main classification: F25B1
IPC codes: F25B27