Patent Publication Number: US-2022213812-A1

Title: Single-working-medium vapor combined cycle

Description:
FIELD 
     The present invention belongs to the flied of energy and power technology. 
     BACKGROUND 
     Cold demand, heat demand and power demand are common in human life and production. It is an important way to obtain and provide power by the conversion of thermal energy into mechanical energy. In general, the temperature of heat source reduces and varies with the release of heat. When fossil fuels are used as the primary energy, the heat source has the dual characteristics of both high temperature and variable temperature. Therefore, only one single thermodynamic cycle cannot achieve an ideal efficiency for refrigeration, heating or power generation. 
     Take the vapor power device with external combustion for example, its heat source has the dual characteristics of high temperature and variable temperature. For those vapor power devices based on the Rankine cycle, the material&#39;s temperature resistance and pressure resistance abilities and safety concerns limit the parameters of the cycle&#39;s working medium. Therefore, there is a big temperature difference between the working medium and the heat source, which leads to big irreversible loss and low efficiency. 
     Humans need new basic theory of thermal science to use fuel or other high temperature thermal energy simply, actively, efficiently for achieving refrigeration, heating or power. In the basic theory system of thermal science, thermodynamic cycles are the theoretical basis of thermal energy utilization devices, and the core of energy utilization systems. The establishment, development and application of thermodynamic cycles will play an important role in the rapid development of energy utilization and will promote actively for social progress and productivity development. 
     Based on the principles of simple, active and efficient utilization of temperature difference, aiming at the power generation application of high temperature heat sources or variable temperature heat sources, and striving to provide theoretical support for the simplification and high efficiency of thermo-power systems, the present invention proposes a single-working-medium vapor combined cycle. 
     THE CONTENTS OF THE PRESENT INVENTION 
     The single working-medium vapor combined cycle and the vapor power device for combined cycle are mainly provided in the present invention, and the specific content of the present invention is as follows: 
     1. A single-working-medium vapor combined cycle method consisting of eight processes which are conducted with M 1  kg of working medium and M 2  kg of working medium separately or jointly: performing a pressurization process to set a state (1) to (2) of the M 1  kg of working medium, performing a heat-absorption and vaporization process to set the state (2) to (3) of the M 1  kg of working medium, performing a depressurization process to set the state (3) to (4) of the M 1  kg of working medium, performing a pressurization process to set a state (7) to (4) of the M 2  kg of working medium, performing a heat-absorption process to set a state (4) to (5) of the M 3  kg of working medium, performing a depressurization process to set the state (5) to (6) of the M 3  kg of working medium, performing a heat-releasing process to set the state (6) to (7) of the M 3  kg of working medium, performing a heat-releasing and condensation process to set a state (7) to (1) of the M 1  kg of working medium, wherein M 3  is a sum of M 1  and M 2 . 
     2. A single-working-medium vapor combined cycle method consisting of eleven processes which are conducted with M 1  kg of working medium and M 2  kg of working medium separately or jointly: performing a pressurization process to set a state (1) to (2) of the M 1  kg of working medium, performing a heat-absorption and vaporization process to set the state (2) to (3) of the M 1  kg of working medium, performing a depressurization process to set the state (3) to (4) of the M 1  kg of working medium, performing a pressurization process to set a state (9) to (4) of the M 2  kg of working medium, performing a heat-absorption process to set a state (4) to (5) of the M 3  kg of working medium, performing a depressurization process to set a state (5) to (8) of the X kg of working medium, performing a heat-absorption process to set a state (5) to (6) of the (M 3 −X) kg of working medium, performing a depressurization process to set the state (6) to (7) of the (M 3 −X) kg of working medium, performing a heat-releasing process to set the state (7) to (8) of the (M 3 −X) kg of working medium, performing a heat-releasing process to set a state (8) to (9) of the M 3  kg of working medium, performing a heat-releasing and condensation process to set a state (9) to (1) of the M 1  kg of working medium, wherein M 3  is a sum of M 1  and M 2 . 
     3. A single-working-medium vapor combined cycle method consisting of eleven processes which are conducted with M 1  kg of working medium and M 2  kg of working medium separately or jointly: performing a pressurization process to set a state (1) to (2) of the M 1  kg of working medium, performing a heat-absorption process to set the state (2) to (b) of the M 1  kg of working medium, performing a heat-absorption and vaporization process to set a state (b) to (3) of the (M 1 +M) kg of working medium, performing a depressurization process to set the state (3) to (4) of the (M 1 +M) kg of working medium, performing a pressurization process to set a state (7) to (a) of the M 2  kg of working medium, performing a heat-releasing and condensation process to set a state (a) to (b) of the M kg of working medium, performing a pressurization process to set a state (a) to (4) of the (M 2 −M) kg of working medium, performing a heat-absorption process to set a state (4) to (5) of the M 3  kg of working medium, performing a depressurization process to set the state (5) to (6) of the M 3  kg of working medium performing a heat-releasing process to set the state (6) to (7) of the M 3  kg of working medium, performing a heat-releasing and condensation process to set a state (7) to (1) of the M 1  kg of working medium, wherein M 3  is a sum of M 1  and M 2 . 
     4. A single-working-medium vapor combined cycle method consisting of fourteen processes which are conducted with M 1  kg of working medium and M 2  kg of working medium separately or jointly: performing a pressurization process to set a state (1) to (2) of the M 1  kg of working medium, performing a heat-absorption process to set the state (2) to (b) of the M 1  kg of working medium, performing a heat-absorption and vaporization process to set a state (b) to (3) of the (M 1 +M) kg of working medium, performing a depressurization process to set the state (3) to (4) of the (M 1 +M) kg of working medium, performing a pressurization process to set a state (9) to (a) of the M 2  kg of working medium, performing a heat-releasing and condensation process to set a state (a) to (b) of the M kg of working medium, performing a pressurization process to set a state (a) to (4) of the (M 2 −M) kg of working medium, performing a heat-absorption process to set a state (4) to (5) of the M 3  kg of working medium, performing a depressurization process to set a state (5) to (8) of the X kg of working medium, performing a heat-absorption process to set a state (5) to (6) of the (M 3 −X) kg of working medium, performing a depressurization process to set the state (6) to (7) of the (M 3 −X) kg of working medium, performing a heat-releasing process to set the state (7) to (8) of the (M 3 −X) kg of working medium, performing a heat-releasing process to set a state (8) to (9) of the M 3  kg of working medium, performing a heat-releasing and condensation process to set a state (9) to (1) of the M 1  kg of working medium, wherein M 3  is a sum of M 1  and M 2 . 
     5. A single-working-medium vapor combined cycle method consisting of nine processes which are conducted with M 1  kg of working medium and M 2  kg of working medium separately or jointly: performing a pressurization process to set a state (1) to (2) of the M 1  kg of working medium, performing a heat-absorption and vaporization process to set the state (2) to (3) of the M 1  kg of working medium, performing a depressurization process to set the state (3) to (4) of the M 1  kg of working medium, performing a pressurization process to set a state (7) to (4) of the M 2  kg of working medium, performing a heat-absorption process to set a state (4) to (5) of the M 3  kg of working medium, performing a depressurization process to set the state (5) to (6) of the M 3  kg of working medium, performing a heat-releasing process to set the state (6) to (7) of the M 3  kg of working medium, performing a depressurization process to set a state (7) to (8) of the M 1  kg of working medium, performing a heat-releasing and condensation process to set the state (8) to (1) of the M 1  kg of working medium, wherein M 3  is a sum of M 1  and M 2 . 
     6. A single-working-medium vapor combined cycle method consisting of twelve processes which are conducted with M 1  kg of working medium and M 2  kg of working medium separately or jointly: performing a pressurization process to set a state (1) to (2) of the M 1  kg of working medium, performing a heat-absorption and vaporization process to set the state (2) to (3) of the M 1  kg of working medium, performing a depressurization process to set the state (3) to (4) of the M 1  kg of working medium, performing a pressurization process to set a state (9) to (4) of the M 2  kg of working medium, performing a heat-absorption process to set a state (4) to (5) of the M 3  kg of working medium, performing a depressurization process to set a state (5) to (8) of the X kg of working medium, performing a heat-absorption process to set a state (5) to (6) of the (M 3 −X) kg of working medium, performing a depressurization process to set the state (6) to (7) of the (M 3 −X) kg of working medium, performing a heat-releasing process to set the state (7) to (8) of the (M 3 −X) kg of working medium, performing a heat-releasing process to set a state (8) to (9) of the M 3  kg of working medium, performing a depressurization process to set a state (9) to (c) of a M 1  kg of working medium, performing a heat-releasing and condensation process to set the state (c) to (1) of the M 1  kg of working medium, wherein M 3  is a sum of M 1  and M 2 . 
     7. A single-working-medium vapor combined cycle method consisting of twelve processes which are conducted with M 1  kg of working medium and M 2  kg of working medium separately or jointly: performing a pressurization process to set a state (1) to (2) of the M 1  kg of working medium, performing a heat-absorption process to set the state (2) to (b) of the M 1  kg of working medium, performing a heat-absorption and vaporization process to set a state (b) to (3) of the (M 1 +M) kg of working medium, performing a depressurization process to set the state (3) to (4) of the (M 1 +M) kg of working medium, performing a pressurization process to set a state (7) to (a) of the M 2  kg of working medium, performing a heat-releasing and condensation process to set a state (a) to (b) of the M kg of working medium, performing a pressurization process to set a state (a) to (4) of the (M 2 −M) kg of working medium, performing a heat-absorption process to set a state (4) to (5) of the M 3  kg of working medium, performing a depressurization process to set the state (5) to (6) of the M 3  kg of working medium, performing a heat-releasing process to set the state (6) to (7) of the M 3  kg of working medium, performing a depressurization process to set the state (7) to (8) of the M 1  kg of working medium, performing a heat-releasing and condensation process to set the state (8) to (1) of the M 1  kg of working medium, wherein M 3  is a sum of M 1  and M 2 . 
     8. A single-working-medium vapor combined cycle method consisting of fifteen processes which are conducted with M 1  kg of working medium and M 2  kg of working medium separately or jointly: performing a pressurization process to set a state (1) to (2) of the M 1  kg of working medium, performing a heat-absorption process to set the state (2) to (b) of the M 1  kg of working medium, performing a heat-absorption and vaporization process to set a state (b) to (3) of the (M 1 +M) kg of working medium, performing a depressurization process to set the state (3) to (4) of the (M 1 +M) kg of working medium, performing a pressurization process to set a state (9) to (a) of the M 2  kg of working medium, performing a heat-releasing and condensation process to set a state (a) to (b) of the M kg of working medium, performing a pressurization process to set a state (a) to (4) of the (M 2 −M) kg of working medium, performing a heat-absorption process to set the state (4) to (5) of the M 3  kg of working medium, performing a depressurization process to set a state (5) to (8) of the X kg of working medium, performing a heat-absorption process to set a state (5) to (6) of the (M 3 −X) kg of working medium, performing a depressurization process to set the state (6) to (7) of the (M 3 −X) kg of working medium, performing a heat-releasing process to set the state (7) to (8) of the (M 3 −X) kg of working medium, performing a heat-releasing process to set a state (8) to (9) of the M 3  kg of working medium, performing a depressurization process to set a state (9) to (c) of the M 1  kg of working medium, performing a heat-releasing and condensation process to set the state (c) to (1) of the M 1  kg of working medium, wherein M 3  is a sum of M 1  and M 2 . 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  is a type 1 example general flow chart of a single-working-medium vapor combined cycle provided in the present invention. 
         FIG. 2  is a type 2 example general flow chart of a single-working-medium vapor combined cycle provided in the present invention. 
         FIG. 3  is a type 3 example general flow chart of a single-working-medium vapor combined cycle provided in the present invention. 
         FIG. 4  is a type 4 example general flow chart of a single-working-medium vapor combined cycle provided in the present invention. 
         FIG. 5  is a type 5 example general flow chart of a single-working-medium vapor combined cycle provided in the present invention. 
         FIG. 6  is a type 6 example general flow chart of a single-working-medium vapor combined cycle provided in the present invention. 
         FIG. 7  is a type 7 example general flow chart of a single-working-medium vapor combined cycle provided in the present invention. 
         FIG. 8  is a type 8 example general flow chart of a single-working-medium vapor combined cycle provided in the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     The first thing to note is that, when describing the cycle&#39;s structures and processes, the processes will not be repeatedly described if not necessary, and the obvious processes will not be described. In each of the following examples, M 3  is a sum of M 1  and M 2 . The detailed description of the present invention is as follows: 
     The T-s diagram of the single-working-medium vapor combined cycle in  FIG. 1  works as follows: 
     (1) From the perspective of the cycle&#39;s processes. 
     The working medium conducts eight processes: a pressurization process  1 - 2  of the M 1  kg of working medium, a heat-absorption vaporization and superheating process  2 - 3  of the M 1  kg of working medium, a depressurization process  3 - 4  of the M 1  kg of working medium, a pressurization process  7 - 4  of M 2  kg of working medium, a heat-absorption process  4 - 5  of the M 3  kg of working medium, a depressurization process  5 - 6  of the M 3  kg of working medium, a heat-releasing process  6 - 7  of the M 3  kg of working medium, a heat-releasing and condensation process  7 - 1  of the M 1  kg of working medium. 
     (2) From the perspective of energy conversion. 
     {circle around (1)} Heat absorption processes: the process  2 - 3  of the M 1  kg of working medium and the process  5 - 6  of the M 3  kg of working medium. The relatively high-temperature part of the absorbed heat is usually provided by an external heat source; the relatively low-temperature part of the absorbed heat can be provided by an external heat source, or by the heat-releasing process  6 - 7  of the M 3  kg of working medium (regeneration), or by both. 
     {circle around (2)} Heat-releasing processes. The heat released by the M 3  kg of working medium in process  6 - 7  can be sent externally to meet the corresponding heat demand, or used for the heat absorption demand of other processes in the combined cycle partially or completely; the useless part is released to a low-temperature heat sink (such as the environment). The heat released by the M 1  kg of working medium in process  7 - 1  is usually released to the low-temperature heat sink, or be supplied to the heat user when cogeneration is applicable. 
     {circle around (3)} Energy conversion processes. The pressurization process  1 - 2  of the M 1  kg of working medium is usually achieved by a pump. The pressurization process  7 - 4  of the M 2  kg of working medium is usually achieved by a compressor. The depressurization (and expansion) process  3 - 4  of the M 1  kg of working medium and the depressurization (and expansion) process  5 - 6  of the M 3  kg of working medium are usually achieved by expanders. The total expansion work output is greater than the total pressurization work input; therefore, thermal energy is converted into power (the cycle&#39;s net work), and the single-working-medium vapor combined cycle is completed. 
     The T-s diagram of the single-working-medium vapor combined cycle in  FIG. 2  works as follows: 
     (1) From the perspective of the cycle&#39;s processes. 
     The working medium conducts eleven processes: a pressurization process  1 - 2  of the M 1  kg of working medium, a heat-absorption vaporization and superheating process  2 - 3  of the M 1  kg of working medium, a depressurization process  3 - 4  of the M 1  kg of working medium, a pressurization process  9 - 4  of M 2  kg of working medium, a heat-absorption process  4 - 5  of the M 3  kg of working medium, a depressurization process  5 - 8  of the X kg of working medium, a heat-absorption process  5 - 6  of the (M 3 −X) kg of working medium, a depressurization process  6 - 7  of the (M 3 −X) kg of working medium, a heat-releasing process  7 - 8  of the (M 3 −X) kg of working medium, a heat-releasing process  8 - 9  of the M 3  kg of working medium, a heat-releasing and condensation process  9 - 1  of the M 1  kg of working medium. 
     (2) From the perspective of energy conversion. 
     {circle around (1)} Heat absorption processes: the process  2 - 3  of the M 1  kg of working medium, the process  4 - 5  of the M 3  kg of working medium and the process  5 - 6  of the (M 3 −X) kg of working medium. The relatively high-temperature part of the absorbed heat is usually provided by an external heat source; the relatively low-temperature part of the absorbed heat can be provided by an external heat source, or by the heat-releasing process  7 - 8  of the (M 3 −X) kg of working medium and the heat-releasing process  8 - 9  of the M 3  kg of working medium (regeneration), or by both. 
     {circle around (2)} Heat-releasing processes. The heat released by the (M 3 −X) kg of working medium in process  7 - 8  and the heat released by the M 3  kg of working medium in process  8 - 9  can be sent externally to meet the corresponding heat demand, or used for the heat absorption demand of other processes in the combined cycle partially or completely; the useless part is released to a low-temperature heat sink (such as the environment). The heat released by the M 1  kg of working medium in process  9 - 1  is usually released to the low-temperature heat sink, or be supplied to the heat user when cogeneration is applicable. 
     {circle around (3)} Energy conversion processes. The pressurization process  1 - 2  of M 1  kg of working medium is usually achieved by a pump. The pressurization process  9 - 4  of M 2  kg of working medium is usually achieved by a compressor. The depressurization process  3 - 4  of M 1  kg of working medium, the depressurization process  5 - 8  of X kg of working medium and the depressurization process  6 - 7  of (M 3 −X) kg of working medium are usually achieved by expanders. The total expansion work output is greater than the total pressurization work input; therefore, thermal energy is converted into power (the cycle&#39;s net work), and the single-working-medium vapor combined cycle is completed. 
     The T-s diagram of the single-working-medium vapor combined cycle in  FIG. 3  works as follows: 
     (1) From the perspective of the cycle&#39;s processes. 
     The working medium conducts eleven processes: a pressurization process  1 - 2  of the M 1  kg of working medium, a mixing heat-absorption process  2 - b  of the M 1  kg of working medium and the M kg of working medium, a heat-absorption vaporization and superheating process b- 3  of the (M 1 +M) kg of working medium, a depressurization process  3 - 4  of the (M 1 +M) kg of working medium, a pressurization process  7 - a  of the M 2  kg of working medium, a mixing heat-absorption process a-b of the M 1  kg of working medium and the M kg of working medium, a pressurization process a- 4  of the (M 2 −M) kg of working medium, a heat-absorption process  4 - 5  of the M 3  kg of working medium, a depressurization process  5 - 6  of M 3  kg of working medium, a heat-releasing process  6 - 7  of the M 3  kg of working medium, a heat-releasing and condensation process  7 - 1  of the M 1  kg of working medium. 
     (2) From the perspective of energy conversion. 
     {circle around (1)} Heat absorption processes: the mixing heat released by the M kg of working medium is absorbed by the process  2 - b  of the M 1  kg of working medium. For the process b- 3  of the M 1  kg of working medium and the process  4 - 5  of the M 3  kg of working medium, the relatively high-temperature part of the absorbed heat is usually provided by an external heat source; the relatively low-temperature part of the absorbed heat can be provided by an external heat source, or by the heat-releasing process  6 - 7  of M 3  the kg of working medium (regeneration), or by both. 
     {circle around (2)} Heat-releasing processes. The heat released by the M 3  kg of working medium in process  6 - 7  can be sent externally to meet the corresponding heat demand, or used for the heat absorption demand of other processes in the combined cycle partially or completely; the useless part is released to a low-temperature heat sink (such as the environment). The heat released by the M 1  kg of working medium in process  7 - 1  is usually released to the low-temperature heat sink, or be supplied to the heat user when cogeneration is applicable. 
     {circle around (3)} Energy conversion processes. The pressurization process  1 - 2  of the M 1  kg of working medium is usually achieved by a pump. The pressurization process  7 - a  of the M 2  kg of working medium and the pressurization process a- 4  of the (M 2 −M) kg of working medium are usually achieved by a compressor. The depressurization process  3 - 4  of the (M 1 +M) kg of working medium, the depressurization process  5 - 6  of the M 3  kg of working medium is usually achieved by expander. The total expansion work output is greater than the total pressurization work input; therefore, thermal energy is converted into power (the cycle&#39;s net work), and the single-working-medium vapor combined cycle is completed. 
     The T-s diagram of the single-working-medium vapor combined cycle in  FIG. 4  works as follows: 
     (1) From the perspective of the cycle&#39;s processes. 
     The working medium conducts eleven processes: a pressurization process  1 - 2  of the M 1  kg of working medium, a mixing heat-absorption process  2 - b  of the M 1  kg of working medium and the M kg of working medium, a heat-absorption vaporization and superheating process b- 3  of the (M 1 +M) kg of working medium, a depressurization process  3 - 4  of the (M 1 +M) kg of working medium, a pressurization process  9 - a  of the M 2  kg of working medium, a mixing heat-absorption process a-b of the M 1  kg of working medium and the M kg of working medium, a pressurization process a- 4  of the (M 2 −M) kg of working medium, a heat-absorption process  4 - 5  of the M 3  kg of working medium, a depressurization process  5 - 8  of the X kg of working medium, a heat-absorption process  5 - 6  of the (M 3 −X) kg of working medium, a depressurization process  6 - 7  of the (M 3 −X) kg of working medium, a heat-releasing process  7 - 8  of the (M 3 −X) kg of working medium, a heat-releasing process  8 - 9  of the M 3  kg of working medium, a heat-releasing and condensation process  9 - 1  of the M 1  kg of working medium. 
     (2) From the perspective of energy conversion. 
     {circle around (1)} Heat absorption processes: the mixing heat released by the M kg of working medium is absorbed by the process  2 - b  of the M 1  kg of working medium. For the process b- 3  of the (M 1 +M) kg of working medium, the process  4 - 5  of the M 3  kg of working medium and the process  5 - 6  of the (M 3 −X) kg of working medium, the relatively high-temperature part of the absorbed heat is usually provided by an external heat source; the relatively low-temperature part of the absorbed heat can be provided by an external heat source, or by the combination of heat-releasing process  7 - 8  of the (M 3 −X) kg of working medium and heat-releasing process  8 - 9  of the M 3  kg of working medium (regeneration), or by both. 
     {circle around (2)} Heat-releasing processes. The heat released by the (M 3 −X) kg of working medium in process  7 - 8  and the heat released by the M 3  kg of working medium in process  8 - 9  can be sent externally to meet the corresponding heat demand, or used for the heat absorption demand of other processes in the combined cycle partially; the useless part is released to a low-temperature heat sink (such as the environment). The heat released by the M 1  kg of working medium in  9 - 1  process is usually released to the low-temperature heat sink, or be supplied to the heat user when cogeneration is applicable. 
     {circle around (3)} Energy conversion processes. The pressurization process  1 - 2  of the M 1  kg of working medium is usually achieved by a pump. The pressurization process  9 - a  of the M 2  kg of working medium an the pressurization process a- 4  of the (M 2 −M) kg of working medium are usually achieved by compressors. The depressurization process  3 - 4  of the (M 1 +M) kg of working medium, the depressurization process  5 - 8  of the X kg of working medium and the depressurization process  6 - 7  of the (M 3 −X) kg of working medium are usually achieved by expanders. The total expansion work output is greater than the total pressurization work input; therefore, thermal energy is converted into power (the cycle&#39;s net work), and the single-working-medium vapor combined cycle is completed. 
     The T-s diagram of the single-working-medium vapor combined cycle in  FIG. 5  works as follows: 
     (1) From the perspective of the cycle&#39;s processes. 
     The working medium conducts nine processes: a pressurization process  1 - 2  of the M 1  kg of working medium, a heat-absorption vaporization and superheating process  2 - 3  of the M 1  kg of working medium, a depressurization process  3 - 4  of the M 1  kg of working medium, a pressurization process  7 - 4  of the M 2  kg of working medium, a heat-absorption process  4 - 5  of the M 3  kg of working medium, a depressurization process  5 - 6  of the M 3  kg of working medium, a heat-releasing process  6 - 7  of the M 3  kg of working medium, a depressurization process  7 - 8  of the M 1  kg of working medium, a heat-releasing and condensation process  8 - 1  of the M 1  kg of working medium. 
     (2) From the perspective of energy conversion. 
     {circle around (1)} Heat absorption processes: for the process  2 - 3  of the M 1  kg of working medium and the process  4 - 5  of the M 3  kg of working medium, the relatively high-temperature part of the absorbed heat is usually provided by an external heat source; the relatively low-temperature part of the absorbed heat can be provided by an external heat source, or by the combination of heat-releasing process  6 - 7  of the M 3  kg of working medium, or by both. 
     {circle around (2)} Heat-releasing processes. The heat released by the M 3  kg of working medium in process  6 - 7  can be sent externally to meet the corresponding heat demand, or used for the heat absorption demand of other processes in the combined cycle partially; the useless part is released to a low-temperature heat sink (such as the environment). The heat released by the M 1  kg of working medium in process  8 - 1  is usually released to the low-temperature heat sink, or be supplied to the heat user when cogeneration is applicable. 
     {circle around (3)} Energy conversion processes. The pressurization process  1 - 2  of the M 1  kg of working medium is usually achieved by a pump. The pressurization process  7 - 4  of the M 2  kg of working medium is usually achieved by a compressor. The depressurization process  3 - 4  of the M 1  kg of working medium, the depressurization process  5 - 6  of the M 3  kg of working medium and the depressurization process  7 - 8  of the M 1  kg of working medium are usually achieved by expanders. The total expansion work output is greater than the total pressurization work input; therefore, thermal energy is converted into power (the cycle&#39;s net work), and the single-working-medium vapor combined cycle is completed. 
     The T-s diagram of the single-working-medium vapor combined cycle in  FIG. 6  works as follows: 
     (1) From the perspective of the cycle&#39;s processes. 
     The working medium conducts twelve processes: a pressurization process  1 - 2  of the M 1  kg of working medium, a heat-absorption vaporization and superheating process  2 - 3  of the M 1  kg of working medium, a depressurization process  3 - 4  of the M 1  kg of working medium, a pressurization process  9 - 4  of the M 2  kg of working medium, a heat-absorption process  4 - 5  of the M 3  kg of working medium, a depressurization process  5 - 8  of the X kg of working medium, a heat-absorption process  5 - 6  of the (M 3 −X) kg of working medium, a depressurization process  6 - 7  of the (M 3 −X) kg of working medium, a heat-releasing process  7 - 8  of the (M 3 −X) kg of working medium, a heat-releasing process  8 - 9  of the M 3  kg of working medium, a depressurization process  9 - c  of the M 1  kg of working medium, a heat-releasing and condensation process c- 1  of the M 1  kg of working medium. 
     (2) From the perspective of energy conversion. 
     {circle around (1)} Heat absorption processes: the process  2 - 3  of the M 1  kg of working medium, the process  4 - 5  of the M 3  kg of working medium and the process  5 - 6  of the (M 3 −X) kg of working medium. The relatively high-temperature part of the absorbed heat is usually provided by an external heat source; the relatively low-temperature part of the absorbed heat can be provided by an external heat source, or by the combination of heat-releasing process  7 - 8  of the (M 3 −X) kg of working medium and heat-releasing process  8 - 9  of the M 3  kg of working medium (regeneration), or by both. 
     {circle around (2)} Heat-releasing processes. The heat released by the (M 3 −X) kg of working medium in process  7 - 8  and the heat released by the M 3  kg of working medium in process  8 - 9  can be sent externally to meet the corresponding heat demand, or used for the heat absorption demand of other processes in the combined cycle partially; the useless part is released to a low-temperature heat sink (such as the environment). The heat released by the M 1  kg of working medium in process c- 1  is usually released to the low-temperature heat sink, or be supplied to the heat user when cogeneration is applicable. 
     {circle around (3)} Energy conversion processes. The pressurization process  1 - 2  of the M 1  kg of working medium is usually achieved by a pump. The pressurization process  9 - 4  of the M 2  kg of working medium is usually achieved by a compressor. The depressurization process  3 - 4  of the M 1  kg of working medium, the depressurization process  5 - 8  of the X kg of working medium and the depressurization process  6 - 7  of the (M 3 −X) kg of working medium are usually achieved by expanders. The total expansion work output is greater than the total pressurization work input; therefore, thermal energy is converted into power (the cycle&#39;s net work), and the single-working-medium vapor combined cycle is completed. 
     The T-s diagram of the single-working-medium vapor combined cycle in  FIG. 7  works as follows: 
     (1) From the perspective of the cycle&#39;s processes. 
     The working medium conducts twelve processes: a pressurization process  1 - 2  of the M 1  kg of working medium, a mixing heat-absorption process  2 - b  of the M 1  kg of working medium and the M kg of working medium, a heat-absorption vaporization and superheating process b- 3  of the (M 1 +M) kg of working medium, a depressurization process  3 - 4  of the (M 1 +M) kg of working medium, a pressurization process  7 - a  of the M 2  kg of working medium, a mixing heat-absorption process a-b of the M 1  kg of working medium and the M kg of working medium, a pressurization process a- 4  of the (M 2 −M) kg of working medium, a heat-absorption process  4 - 5  of the M 3  kg of working medium, a depressurization process  5 - 6  of the M 3  kg of working medium, a heat-releasing process  6 - 7  of the M 3  kg of working medium, a depressurization process  7 - 8  of the M 1  kg of working medium, a heat-releasing and condensation process  8 - 1  of M 1  kg of working medium. 
     (2) From the perspective of energy conversion. 
     {circle around (1)} Heat absorption processes. The heat to be absorbed by the M 1  kg of working medium in process  2 - b  is released by the M kg of superheated vapor during the mixing process. As for the process b- 3  of the M 1  kg of working medium and the process  4 - 5  of the M 1  kg of working medium, the relatively high-temperature part of the absorbed heat is usually provided by an external heat source; the relatively low-temperature part of the absorbed heat can be provided by an external heat source, or by the heat-releasing process  6 - 7  of the M 3  kg of working medium (regeneration), or by both. 
     {circle around (2)} Heat-releasing processes. The heat released by the M 3  kg of working medium in process  6 - 7  can be sent externally to meet the corresponding heat demand, or used for the heat absorption demand of other processes in the combined cycle partially or completely; the useless part is released to a low-temperature heat sink (such as the environment). The heat released by the M 1  kg of working medium in process  8 - 1  is usually released to the low-temperature heat sink, or be supplied to the heat user when cogeneration is applicable. 
     {circle around (3)} Energy conversion processes. The pressurization process  1 - 2  of the M 1  kg of working medium is usually achieved by a pump. The pressurization process  7 - a  of the M 2  kg of working medium and the pressurization process a- 4  of the (M 2 −M) kg of working medium are usually achieved by compressors. The depressurization process  3 - 4  of the (M 1 +M) kg of working medium and the depressurization (and expansion) process  5 - 6  of the M 3  kg of working medium are usually achieved by expanders. The total expansion work output is greater than the total pressurization work input; therefore, thermal energy is converted into power (the cycle&#39;s net work), and the single-working-medium vapor combined cycle is completed. 
     The T-s diagram of the single-working-medium vapor combined cycle in  FIG. 8  works as follows: 
     (1) From the perspective of the cycle&#39;s processes. The working medium conducts fifteen processes: a pressurization process  1 - 2  of the M 1  kg of working medium, a mixing heat-absorption process  2 - b  of the M 1  kg of working medium and the M kg of working medium, a heat-absorption vaporization and superheating process b- 3  of the (M 1 +M) kg of working medium, a depressurization process  3 - 4  of the (M 1 +M) kg of working medium, a pressurization process  9 - a  of the M 2  kg of working medium, a mixing heat-absorption process a-b of the M 1  kg of working medium and the M kg of working medium, a pressurization process a- 4  of the (M 2 −M) kg of working medium, a heat-absorption process  4 - 5  of the M 3  kg of working medium, a depressurization process  5 - 8  of the X kg of working medium, a heat-absorption process  5 - 6  of the (M 3 −X) kg of working medium, a depressurization process  6 - 7  of the (M 3 −X) kg of working medium, a heat-releasing process  7 - 8  of the (M 3 −X) kg of working medium, a heat-releasing process  8 - 9  of the M 3  kg of working medium, a depressurization process  9 - c  of the M 1  kg of working medium, a heat-releasing and condensation process c- 1  of the M 1  kg of working medium. 
     (2) From the perspective of energy conversion. {circle around (1)} Heat absorption processes. The heat to be absorbed by the M 1  kg of working medium in process  2 - b  is released by the M kg of superheated vapor during the mixing process. As for the process b- 3  of the (M 1 +M) kg of working medium, the process  4 - 5  of the M 3  kg of working medium and the process  5 - 6  of the (M 3 −X) kg of working medium, the relatively high-temperature part of the absorbed heat is usually provided by an external heat source; the relatively low-temperature part of the absorbed heat can be provided by an external heat source, or by the heat-releasing process  7 - 8  of the (M 3 −X) kg of working medium and the heat-releasing process  8 - 9  of the M 3  kg of working medium (regeneration), or by both. 
     {circle around (2)} Heat-releasing processes. The heat released by the (M 3 −X) kg of working medium in process  7 - 8  and the M 3  kg of working medium in process  8 - 9  can be sent externally to meet the corresponding heat demand, or used for the heat absorption demand of other processes in the combined cycle partially; the useless part is released to a low-temperature heat sink (such as the environment). The heat released by the M 1  kg of working medium in process c- 1  is usually released to the low-temperature heat sink, or be supplied to the heat user when cogeneration is applicable. 
     {circle around (3)} Energy conversion processes. The pressurization process  1 - 2  of the M 1  kg of working medium is usually achieved by a pump. The pressurization process  9 - a  of the M 2  kg of working medium and the pressurization process a- 4  of the (M 2 −M) kg of working medium are usually achieved by compressors. The depressurization process  3 - 4  of the (M 1 +M) kg of working medium, the depressurization process  5 - 8  of the X kg of working medium, the depressurization process  6 - 7  of the (M 3 −X) kg of working medium and the depressurization process  9 - c  of the M 1  kg of working medium are usually achieved by expanders. The total expansion work output is greater than the total pressurization work input; therefore, thermal energy is converted into power (the cycle&#39;s net work), and the single-working-medium vapor combined cycle is completed. 
     The Technical Effects of the Present Invention Invention: 
     The single-working-medium vapor combined cycle proposed by the present invention has the following effects and advantages: 
     (1) A basic theory of thermal energy (temperature difference) utilization has been created. 
     (2) The present invention greatly reduces the amount of heat absorbed in the phase-change region, and correspondingly increases the amount of heat absorbed in the high-temperature region or the variable temperature region. Therefore, the single-working-medium vapor combined cycle can achieve high efficiency. 
     (3) The present invention possesses simple methods, reasonable processes and good applicability. It is a common technology to realize the effective utilization of temperature differences. 
     (4) The present invention only uses a single working medium, which is easy to produce and store; The present invention can also reduce the operation cost and improve the flexibility of cycle regulation. 
     (5) The processes in the present invention are shared and reduced, which provides a theoretical basis for reducing equipment investment. 
     (6) In the high temperature region or the variable temperature region, both the cycle&#39;s working medium and the heat source medium conduct variable-temperature processes; therefore, the temperature difference loss is reduced and the efficiency is improved. 
     (7) The present invention adopts the low-pressure and high-temperature operation mode in the high-temperature region; therefore, the contradiction among thermal efficiency, the working medium&#39;s parameters and the material&#39;s temperature resistance and pressure resistance abilities, which is common in traditional vapor power devices, can be resolved. 
     (8) Under the precondition of achieving a high thermal efficiency, the vapor power device provided in the present invention can operate at a low pressure. The present invention provides theoretical support for improving the safety of device operation. 
     (9) The present invention possesses a wide range of applicable working media. The present invention can match energy supply with demand well. It is flexible to match the working medium and the working parameters. 
     (10) The present invention expands the range of thermodynamic cycles for temperature difference utilization, and contributes to a higher-efficiency power generation of high-temperature heat sources and variable-temperature heat sources.