A heat engine unidirectional flow and oscillatory flow heat exchange test platform

Abstract

The application discloses a heat engine one-way flow and oscillation flow heat exchange test platform, and belongs to the technical field of heat engines, which comprises a detachable and replaceable series test section, a compressor assembly, a sensor assembly, a manifold valve assembly, a centrifugal fan and a data acquisition system; the series test section is sequentially assembled by a heater, a regenerator and a cooler. The platform can switch four test modes: a one-way flow mode, an oscillation flow mode, a Stirling refrigeration mode and a Stirling power generation mode; the test is carried out on the same rack by adjusting the valve state, the electric connection mode and the piston phase. The oscillation working condition changes the phase difference between the front and rear pistons by means of two linear compressors and a phase adjusting device, and realizes pure oscillation flow, Stirling reverse circulation and positive circulation respectively. The heat engine one-way flow and oscillation flow heat exchange test platform provided by the application provides test support for the structure optimization of heat engine heat exchangers.

Description

Technical Field

[0001] This invention relates to the field of hot air engine technology, and in particular to a hot air engine unidirectional flow and oscillating flow heat transfer test platform. Background Technology

[0002] Stirling cycle and closed Brayton cycle gas engines have wide heat source adaptability and high thermoelectric conversion efficiency, making them valuable for applications in waste heat recovery and space nuclear power. Heaters, regenerators, and coolers are the core heat exchange components of a gas engine, and their heat exchange capacity and flow resistance directly determine the overall cycle efficiency. Component-level performance testing of heat exchangers is a crucial step in the development of gas engines.

[0003] Current testing methods for heat exchangers in hot air engines mainly include two approaches: whole-machine prototype testing and independent component testing. In whole-machine testing, the heat exchanger is fixedly integrated inside the heat engine, allowing only macroscopic comprehensive indicators such as overall power and efficiency to be obtained. It is difficult to decouple the heat transfer and pressure drop characteristics of the heat exchanger from the coupled influence of components such as pistons and cylinders. Furthermore, the assembly of the heat exchanger with the whole machine makes it inconvenient to conduct single-variable comparative tests using samples with different structures. Comparing multiple heat exchanger schemes requires rebuilding a complete prototype, resulting in high R&D costs, long iteration cycles, and limited measurement point placement within the whole machine, making it difficult to obtain refined parameters of the heat exchanger under oscillating flow conditions.

[0004] Existing independent component testing equipment still has significant limitations: some platforms can only conduct steady-state unidirectional flow tests, which cannot reproduce the reciprocating oscillating flow inside the hot air engine, and the test conditions deviate significantly from the actual conditions; a few oscillating flow test equipment are mostly only for testing the regenerator alone, making it difficult to achieve series testing of the heater-regenerator-cooler triple unit; most benches have fixed flow paths, and unidirectional flow and oscillating flow tests require two sets of equipment, resulting in low equipment reuse rate.

[0005] Meanwhile, the Stirling refrigeration and power generation cycles have specific requirements for the phase difference of the two pistons. Existing platforms are difficult to use for both basic heat exchange tests and Stirling forward and reverse cycle simulations under the same hardware architecture, which is not conducive to the performance comparison of heat exchangers under multiple operating conditions.

[0006] Therefore, there is an urgent need to develop a heat exchange testing platform for hot air engines to solve the problems of difficult decoupling of component performance, inconvenient sample disassembly and assembly, and insufficient compatibility with operating conditions in existing equipment. Summary of the Invention

[0007] The purpose of this invention is to provide a test platform for unidirectional and oscillating flow heat transfer in hot air engines, which solves the problems of existing hot air engine heat exchanger test equipment, such as difficulty in decoupling component performance, inconvenience in disassembling and replacing heat exchanger samples, poor compatibility with test conditions, and inability to achieve unidirectional flow-oscillating flow heat transfer testing and Stirling forward and reverse cycle simulation on the same device.

[0008] To achieve the above objectives, the present invention provides a heat transfer test platform for unidirectional flow and oscillating flow of a hot air engine, including a detachable and replaceable series test section and a compressor assembly; The compressor assembly includes a front-end linear compressor and a rear-end linear compressor; The detachable and replaceable series test section is connected at one end to the front-end linear compressor and centrifugal fan via the intake assembly, and at the other end to the rear-end linear compressor and exhaust section via the exhaust assembly.

[0009] Preferably, the removable and replaceable series test section includes a heater, a regenerator and a cooler connected in series, which are connected by a flange and sealed with a copper gasket. The heater is connected to the intake manifold through the heater intake section. One end of the intake manifold is connected to the centrifugal fan, and the other end is connected to the front-end linear compressor through the intake connection pipe. The cooler is connected to the outlet manifold through the cooler outlet section. One end of the outlet manifold is connected to the exhaust section, and the other end is connected to the rear linear compressor through the outlet connection pipe.

[0010] Preferably, an intake manifold one-way flow valve is installed on the intake manifold connecting the heater intake section and the centrifugal fan; an intake manifold oscillating flow valve is installed on the intake manifold connecting the heater intake section and the intake connection pipeline.

[0011] Preferably, a one-way flow valve is provided on the outlet manifold connecting the cooler outlet section and the exhaust section; an oscillating flow valve is provided on the outlet manifold connecting the cooler outlet section and the outlet connection pipeline.

[0012] Preferably, the heater includes a heater housing, an internal heater located in the inner cavity of the heater housing, and an external heating port located on the outer surface of the heater housing; a heater temperature sensor is arranged on the side wall of the heater housing.

[0013] Preferably, the cooler includes a cooler housing, an internal cooler located in the inner cavity of the cooler housing, and external heat dissipation fins located on the outer surface of the cooler housing; a cooler temperature sensor is arranged in the cooler housing.

[0014] Preferably, the front-end linear compressor and the rear-end linear compressor have the same structure, both including a housing with an integrated piston cylinder, windings, piston, piston connecting rod, leaf spring and gas spring piston; The winding is arranged outside the piston cylinder of the housing, and the piston is located inside the piston cylinder. A working chamber and a back pressure chamber are formed on both sides of the piston between the piston and the housing. The piston connecting rod is connected to the rear end of the piston, and a leaf spring is clamped on the piston connecting rod. A gas spring piston is connected to the rear end of the piston connecting rod. A gas spring chamber is formed between the gas spring piston and the housing.

[0015] Preferably, a working chamber pressure sensor and a gas spring chamber pressure sensor are installed on the outer wall of the housing; the working chamber pressure sensor collects the dynamic changes in pressure within the working chamber; and the gas spring chamber pressure sensor collects the dynamic changes in pressure within the gas spring chamber.

[0016] Therefore, the present invention employs the above-mentioned unidirectional flow and oscillating flow heat transfer test platform for a hot air engine, which has the following beneficial effects: (1) The present invention features a detachable and replaceable series test section. The heater, regenerator, and cooler are connected by modular flanges. In the shutdown state, heat exchanger samples with different structures can be disassembled and replaced individually or as a whole. When conducting comparative tests, the main hardware of the test bench, such as the compressor assembly, manifold valve assembly, and sensor assembly, can be reused. Only the heat exchanger sample under test needs to be replaced to carry out a single variable control experiment. There is no need to rebuild the entire test device, which effectively reduces the iterative development cost of heat exchangers and shortens the sample testing cycle.

[0017] (2) This invention, through the valve opening and closing combination of the manifold valve assembly, can selectively construct unidirectional flow paths and closed oscillating flow loops. The same test platform is compatible with both unidirectional flow and oscillating flow conditions, solving the defect of single operating conditions of traditional equipment and improving the reusability of test bench equipment. By conducting component-level tests on heaters, regenerators, and coolers as independent test sections, the coupling interference of other components of the hot air engine can be avoided, making it easier to directly obtain parameters such as the heat transfer coefficient and flow pressure drop of the heat exchanger itself, and realizing decoupled testing of heat exchanger performance.

[0018] (3) The present invention is equipped with two linear compressors with identical structures and a phase adjustment device. By adjusting the operating phase difference of the pistons of the two linear compressors, in addition to completing the basic heat exchange test of the oscillating flow, it can also reproduce the piston movement law of Stirling refrigeration reverse cycle and Stirling power generation positive cycle. Under the unified test hardware conditions, the heat exchanger performance evaluation under multiple cycle modes can be completed, which is convenient for studying the working characteristics of the heat exchanger under different cycle conditions.

[0019] (4) This platform is equipped with multiple temperature and pressure sensors in the test section and each chamber of the compressor. It can collect dynamic temperature and pressure signals at key locations under oscillating flow, which is convenient for revealing the heat and mass transfer law inside the heat exchanger under oscillating flow conditions, and provides experimental data support for the optimized design of Stirling and closed Brayton cycle heat exchangers.

[0020] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of an embodiment of the present invention; Figure 2The diagram shows the electrical connection and piston phase under the oscillating flow experimental conditions of this invention, wherein (a) is a schematic diagram of the electrical connection and (b) is a piston phase diagram. Figure 3 The diagram shows the electrical connection and piston phase under the refrigeration test conditions of this invention, wherein (a) is a schematic diagram of the electrical connection and (b) is a piston phase diagram. Figure 4 The diagram shows the electrical connection and piston phase under the power generation test conditions of this invention, wherein (a) is a schematic diagram of the electrical connection and (b) is a piston phase diagram.

[0022] Figure label: 1. Centrifugal fan; 2. Intake manifold; 21. Intake manifold one-way valve; 22. Intake manifold oscillating valve; 3. Heater inlet section; 4. Heater; 41. External heating port; 42. Internal heater; 5. Regenerator; 6. Cooler; 61. External heat dissipation fins; 62. Internal cooler; 7. Cooler outlet section; 8. Outlet manifold; 81. Outlet manifold one-way valve; 82. Outlet manifold oscillating valve; 9. Exhaust section; 101. Inlet connection pipe; 102. Outlet connection pipe; 11. Front-end linear compressor; 111. Front-end housing; 112. Front-end working chamber; 113. Front-end winding; 114. Front-end piston; 115. Front-end back pressure chamber; 116. Front-end leaf spring; 117. Front-end piston connecting rod; 118. Front-end gas spring piston; 119. Front-end gas spring chamber. 12. Rear linear compressor; 121. Rear housing; 122. Rear working chamber; 123. Rear winding; 124. Rear piston; 125. Rear back pressure chamber; 126. Rear leaf spring; 127. Rear piston connecting rod; 128. Rear gas spring piston; 129. Rear gas spring chamber. 131. Heater temperature sensor; 132. Cooler temperature sensor; 133. Front working chamber pressure sensor; 134. Front gas spring chamber pressure sensor; 135. Rear gas spring chamber pressure sensor; 136. Rear working chamber pressure sensor. Detailed Implementation

[0023] The following detailed description of embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0024] I. Structure of the Heat Exchange Test Platform This embodiment provides a heat transfer test platform for unidirectional flow and oscillating flow in a hot air engine, such as... Figure 1 As shown, the system includes a detachable and replaceable series test section, a compressor assembly, a sensor assembly, a centrifugal fan 1, a manifold valve assembly, and an exhaust section 9. The detachable and replaceable series test section is assembled by connecting a heater 4, a regenerator 5, and a cooler 6 in series. The heater 4, regenerator 5, and cooler 6 are sealed to each other and to the upstream and downstream pipelines using standardized flanges and copper gaskets. In the shutdown state, the test specimens of a single section or the entire test section can be disassembled and replaced.

[0025] The sensor assembly includes multiple sets of temperature and pressure sensors, namely heater temperature sensor 131, cooler temperature sensor 132, front working chamber pressure sensor 133, front gas spring chamber pressure sensor 134, rear gas spring chamber pressure sensor 135, and rear working chamber pressure sensor 136. The signal output terminals of all sensors are electrically connected to the data acquisition system to synchronously acquire dynamic temperature and pressure data at each measuring point during the test.

[0026] The heater 4 is connected to the heater inlet section 3 at its inlet side, which in turn is connected to the intake manifold 2. The intake manifold 2 has two inlets, which are respectively connected to the outlet of the centrifugal fan 1 and the front-end linear compressor 11. The two inlets of the intake manifold 2 are respectively equipped with an intake manifold one-way flow valve 21 and an intake manifold oscillating flow valve 22. The cooler 6 is connected to the cooler outlet section 7 at its outlet side, which in turn is connected to the outlet manifold 8. The outlet manifold 8 has two outlets, which are respectively connected to the exhaust section 9 and the rear-end linear compressor 12. The two outlets of the outlet manifold 8 are respectively equipped with an outlet manifold one-way flow valve 81 and an outlet manifold oscillating flow valve 82. The front-end linear compressor 11 is connected to the intake manifold 2 via an intake connection pipe 101, and the rear-end linear compressor 12 is connected to the outlet manifold 8 via an outlet connection pipe 102.

[0027] Heater 4 includes a heater housing, an external heating port 41, and an internal heater 42. The heater housing has mounting flanges with sealing grooves at both ends, and copper gaskets are placed in the sealing grooves. The internal heater 42 is a replaceable heat exchange core, and can be a finned, shell-and-tube, or flat heat exchanger structure. The overall shape of heater 4 can be cylindrical, annular, or rectangular. Heater 4 provides a heat source for the working fluid inside the circuit by connecting an external electric heating device or a combustion heating device through the external heating port 41. A sensor mounting position is provided on the heater housing for mounting a heater temperature sensor 131.

[0028] The cooler 6 includes a cooler shell, external heat dissipation fins 61, and an internal cooler 62. The cooler shell has mounting flanges with sealing grooves at both ends, and copper gaskets are arranged in the sealing grooves. The internal cooler 62 is a replaceable heat exchange core, and can be a finned, shell-and-tube, or flat-plate heat exchanger structure. The overall shape of the cooler 6 can be cylindrical, annular, or rectangular. The cooler 6 can be connected to an external chiller unit for forced cooling, and the external heat dissipation fins 61 assist in enhancing heat dissipation. A sensor mounting position is provided on the cooler shell for mounting a cooler temperature sensor 132.

[0029] The regenerator 5 is also equipped with standardized flanges at both ends. The regenerator 5 can be detachably filled with one or more heat storage fillers, such as metal wire mesh, metal foil, or foam metal. Different filler samples can be replaced according to test requirements.

[0030] The compressor assembly includes a front-end linear compressor 11 and a rear-end linear compressor 12, and the two compressors have completely identical structures.

[0031] The front-end linear compressor 11 includes a front-end housing 111, a front-end winding 113, a front-end piston 114, a front-end piston connecting rod 117, a front-end leaf spring 116, and a front-end gas spring piston 118. The front-end winding 113 is arranged on the outside of the cylinder of the front-end housing 111, forming the stator of the linear motor. The front-end piston 114 is reciprocally mounted inside the cylinder, and a permanent magnet is attached to the outside of the front-end piston 114, which cooperates with the front-end winding 113 to generate a linear reciprocating driving force. The front-end piston 114 divides the inner cavity of the cylinder to form a front-end working chamber 112 and a front-end back pressure chamber 115. The front-end working chamber 112 is connected to the intake connection pipe 101. The front piston 114 is fixedly connected to the front piston connecting rod 117 at its tail. A front leaf spring 116 is mounted on the front piston connecting rod 117. The outer edge of the front leaf spring 116 is fixed inside the front housing 111, providing axial elastic support for the piston assembly and limiting radial displacement. The end of the front piston connecting rod 117 is connected to the front gas spring piston 118. The front gas spring piston 118 and the front housing 111 enclose a front gas spring cavity 119. The front housing 111 has sensor interfaces, on which a front working chamber pressure sensor 133 and a front gas spring cavity pressure sensor 134 are respectively installed. The front working chamber pressure sensor 133 collects the dynamic changes in pressure within the front working chamber 112; the front gas spring cavity pressure sensor 134 collects the dynamic changes in pressure within the front gas spring cavity 119. The front linear compressor 11 is equipped with a phase adjustment device to adjust the operating phase difference between the front piston 114 and the rear piston 124.

[0032] The rear linear compressor 12 includes a rear housing 121, a rear winding 123, a rear piston 124, a rear piston connecting rod 127, a rear leaf spring 126, and a rear gas spring piston 128. A rear working chamber 122 and a rear back pressure chamber 125 are formed between the rear piston 124 and the rear housing 121, respectively. A rear gas spring chamber 129 is formed between the rear gas spring piston 128 and the housing. The rear working chamber 122 is connected to the outlet connecting pipe 102. A rear gas spring chamber pressure sensor 135 and a rear working chamber pressure sensor 136 are respectively installed on the rear housing 121. The rear working chamber pressure sensor 136 collects the dynamic changes in pressure within the rear working chamber 122; the rear gas spring chamber pressure sensor 135 collects the dynamic changes in pressure within the rear gas spring chamber 129.

[0033] II. Heat Exchange Test Platform Workflow The complete workflow for conducting tests on this platform is as follows: Loosen the flange bolts while the system is stopped, and assemble the removable and replaceable series test section of the target sample; according to the test mode to be executed, complete the hardware piping and electrical wiring configuration for pipeline valves, heat and cold sources, drive power supply, and phase adjustment device. The target operating parameters for each mode are shown in Table 1. Table 1 Design and Operating Conditions

[0034] This platform has four experimental working modes: Mode 1, Unidirectional Flow Test Mode: Open the inlet manifold unidirectional flow valve 21, open the outlet manifold unidirectional flow valve 81, close the inlet manifold oscillating flow valve 22, close the outlet manifold oscillating flow valve 82, and turn on the centrifugal fan 1. Atmospheric pressure air is blown down by the centrifugal fan through the heater, regenerator, and cooler, and finally blown out to the atmospheric environment through the exhaust section. In this mode, the heat transfer characteristics of different types of heat exchangers under atmospheric pressure and unidirectional flow conditions can be measured.

[0035] Mode 2, oscillating flow experimental condition, such as Figure 2 As shown: Electrical connection configuration, such as Figure 2 As shown in (a): the front winding 113 of the front linear compressor 11 and the rear winding 123 of the rear linear compressor 12 are connected in parallel to the same AC drive power supply. The phase adjustment device is in bypass state and does not apply phase shift processing to the drive electrical signal.

[0036] Piston phase setting, such as Figure 2 As shown in (b): By controlling the output of the drive power supply, the phase difference between the front piston 114 and the rear piston 124 is set to 0°, and the two pistons maintain synchronous reciprocating motion.

[0037] Piping and Test Execution: Close the inlet manifold one-way flow valve 21 and the outlet manifold one-way flow valve 81, and open the inlet manifold oscillating flow valve 22 and the outlet manifold oscillating flow valve 82; evacuate the closed loop and fill it with helium working fluid at the set pressure according to Table 1; start the AC drive power supply, set the operating frequency, heating and cooling temperatures according to Table 1, and conduct heat exchanger heat transfer characteristic tests under oscillating flow conditions; the sensor components collect dynamic temperature and pressure data and upload them to the data acquisition system; turn off the drive power supply after the test.

[0038] Mode 3: Stirling refrigeration test experimental conditions, such as Figure 3 As shown: Electrical connection configuration, such as Figure 3 As shown in (a): the rear winding 123 is directly connected to the AC drive power supply; the power supply circuit of the front winding 113 is connected in series with a phase adjustment device, and the phase-shifted drive signal is output by the phase adjustment device.

[0039] Piston phase setting, such as Figure 3 (b) shows: Adjust the phase adjustment device to set the movement phase of the front piston 114 to be 60° ahead of the phase of the rear piston 124; the front piston 114 acts as an exhaustor and the rear piston 124 acts as a power piston.

[0040] Piping and test execution: Keep the valves in the oscillating flow loop unchanged and maintain the charging pressure specified in Table 1; do not apply external heating to heater 4, and connect the cooling medium to cooler 6; start the drive power supply, set the operating frequency according to Table 1, establish a Stirling reverse cycle inside the closed loop, and conduct heat exchanger performance tests under Stirling refrigeration conditions; the sensor assembly collects test data and transmits it to the data acquisition system; turn off the drive power supply after the test.

[0041] Mode 4: Stirling power generation test experimental conditions, such as Figure 4 As shown: Electrical connection configuration, such as Figure 4 As shown in (a): the continuous AC drive power supply of the front winding 113 and the rear winding 123 is disconnected; the rear winding 123 is connected to the instantaneous excitation pulse power supply, and the front winding 113 has no external drive input; the rear linear compressor 12 is switched to the power generation output mode, and the external power acquisition circuit is used for output power detection; the phase adjustment device is kept connected to constrain the piston phase relationship.

[0042] Piston phase setting, such as Figure 4 (b) shows that by presetting the phase logic through the phase adjustment device, the phase of the front piston 114 is maintained 60° ahead of the phase of the rear piston 124. At this time, the front working chamber 112 acts as the expansion chamber, the rear working chamber 122 acts as the compression chamber, the front piston 114 acts as the gas distribution piston, and the rear piston 124 acts as the power piston.

[0043] Piping and Test Execution: The valve status of the oscillating flow loop and the loop charging pressure are maintained according to the parameters in Table 1; Based on Mode 3, the heater 4 is continuously heated through the external heating port 41, and the cooler 6 is cooled by a cold water jacket or by natural radiation to establish a stable temperature difference between the heater 4 and the cooler 6; an instantaneous excitation pulse is input to the rear winding 123 to trigger the working fluid in the loop to establish a Stirling positive cycle; the piston reciprocates by relying on the thermal expansion and contraction of the working fluid, and the rear linear compressor 12 outputs electrical energy; the sensor assembly synchronously collects temperature, pressure and power generation output parameters to determine the working fluid circulation characteristics and heat exchanger heat exchange characteristics of the Stirling generator; after the test, heating and cooling are stopped, and all electrical circuits are disconnected.

[0044] After all test modes have been completed, the equipment must be shut down, the circuit depressurized, and all components cooled to ambient temperature before the flange bolts can be loosened, the next set of heat exchanger samples can be disassembled and replaced, and the entire test procedure described above can be repeated.

[0045] Therefore, the present invention employs the aforementioned heat exchange test platform for unidirectional flow and oscillating flow of a hot gas engine, which can sequentially conduct unidirectional flow heat exchange tests, pure oscillating flow heat exchange tests, Stirling refrigeration cycle heat exchange tests, and Stirling power generation cycle heat exchange tests. On the same test bench, by simply adjusting the valve status, electrical connection method, piston phase, and hot and cold boundary conditions, the performance comparison test of the heat exchanger under various flow and circulation conditions can be completed without replacing the entire test bench hardware, thus reducing the cost of multi-condition testing.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A heat transfer test platform for unidirectional flow and oscillating flow in a hot air engine, characterized in that, Includes a removable and replaceable tandem test section and compressor assembly; The compressor assembly includes a front-end linear compressor and a rear-end linear compressor; The detachable and replaceable series test section is connected at one end to the front-end linear compressor and centrifugal fan via the air intake assembly, and at the other end to the rear-end linear compressor and exhaust section via the air outlet assembly. The detachable and replaceable series test section includes a heater, a regenerator and a cooler connected in series, which are connected by flanges and sealed with copper gaskets. The heater is connected to the intake manifold through the heater intake section. One end of the intake manifold is connected to the centrifugal fan, and the other end is connected to the front-end linear compressor through the intake connection pipe. The cooler is connected to the outlet manifold through the cooler outlet section. One end of the outlet manifold is connected to the exhaust section, and the other end is connected to the rear linear compressor through the outlet connection pipe. The front-end linear compressor is equipped with a phase adjustment device to adjust the operating phase difference between the front piston of the front-end linear compressor and the rear piston of the rear linear compressor. An intake manifold one-way valve is installed on the intake manifold connecting the heater intake section and the centrifugal fan; an intake manifold oscillating valve is installed on the intake manifold connecting the heater intake section and the intake connection pipeline. A one-way flow valve is installed on the outlet manifold connecting the outlet section and the exhaust section of the cooler; an oscillating flow valve is installed on the outlet manifold connecting the outlet section and the outlet connection pipeline of the cooler. The test platform features unidirectional flow mode, oscillating flow mode, Stirling cooling mode, and Stirling power generation mode. In unidirectional flow mode, the centrifugal fan is turned on, and the atmospheric air is driven by the centrifugal fan to pass through the heater, regenerator and cooler in sequence, and finally discharged to the atmosphere through the exhaust section. In oscillating flow mode, the front winding of the front linear compressor and the rear winding of the rear linear compressor are connected in parallel to the same AC drive power supply, the phase adjustment device is in bypass state, the phase difference between the front piston and the rear piston is 0°, the two pistons maintain synchronous reciprocating motion, and nitrogen working fluid at a set pressure is filled into the closed loop. In Stirling cooling mode, the rear winding is directly connected to the AC drive power supply, and the power supply circuit of the front winding is connected in series with the phase adjustment device; the movement phase of the front piston is 60° ahead of the rear piston, the front piston acts as the discharge device, and the rear piston acts as the power piston; the heater does not apply external heating, and the cooler is connected to the cooling medium. In Stirling power generation mode, the continuous AC drive power supply to the front winding and the rear winding is disconnected; the rear winding is connected to the instantaneous excitation pulse power supply, and the front winding has no external drive input. The rear linear compressor switches to power generation output mode and connects to an external power acquisition circuit; the front piston moves 60° ahead of the rear piston; the front piston acts as the gas distribution piston and the rear piston acts as the power piston; the heater is continuously heated through an external heating port, and the cooler establishes heat dissipation conditions, creating a stable temperature difference between the heater and the cooler.

2. The heat transfer test platform for unidirectional flow and oscillating flow of a hot air engine according to claim 1, characterized in that, The heater includes a heater housing, an internal heater located in the inner cavity of the heater housing, and an external heating port located on the outer surface of the heater housing; a heater temperature sensor is arranged on the side wall of the heater housing.

3. The heat transfer test platform for unidirectional flow and oscillating flow of a hot air engine according to claim 2, characterized in that, The cooler includes a cooler housing, an internal cooler located in the inner cavity of the cooler housing, and external heat dissipation fins located on the outer surface of the cooler housing; the cooler housing is equipped with a cooler temperature sensor.

4. The heat transfer test platform for unidirectional flow and oscillating flow of a hot air engine according to claim 3, characterized in that, The front-end linear compressor and the back-end linear compressor have the same structure, both including a housing with an integrated piston cylinder, windings, piston, piston connecting rod, leaf spring, and gas spring piston; The winding is arranged outside the piston cylinder of the housing, and the piston is located inside the piston cylinder. A working chamber and a back pressure chamber are formed on both sides of the piston between the piston and the housing. The piston connecting rod is connected to the rear end of the piston, and a leaf spring is clamped on the piston connecting rod. A gas spring piston is connected to the rear end of the piston connecting rod. A gas spring chamber is formed between the gas spring piston and the housing.

5. The heat transfer test platform for unidirectional flow and oscillating flow of a hot air engine according to claim 4, characterized in that, The outer wall of the casing is equipped with a working chamber pressure sensor and a gas spring chamber pressure sensor; the working chamber pressure sensor collects the dynamic changes in pressure within the working chamber; the gas spring chamber pressure sensor collects the dynamic changes in pressure within the gas spring chamber.

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