Kwa kituo cha muda mrefu cha Mwezi, kuzalisha umeme pekee hakutoshi. Mifumo ya kusaidia uhai, vifaa vya kisayansi, mifumo ya kielektroniki na maeneo nyeti ya kazi pia yanahitaji ubaridi usiokatika. Tofauti na mitambo duniani, uso wa Mwezi hauna angahewa, hivyo joto taka haliwezi kuondolewa kwa hewa au maji; linaweza tu kutolewa kuelekea angani kupitia radiators. Zaidi ya hayo, halijoto sawa ya heat sink ambayo radiator hukabiliana nayo inaweza kubadilika kutoka takribani 90 K hadi 325 K katika kipindi cha mchana wa Mwezi. Wigo huu mpana unaweza kusababisha cycle inayofanya kazi kwa ufanisi mkubwa katika halijoto ya chini kupoteza utendaji wake wakati wa adhuhuri ya Mwezi au kusimamisha ubaridi kabisa.

Watafiti walitengeneza mifumo saba inayounganisha uzalishaji wa nguvu na ubaridi katika mnyororo mmoja wa nishati ili kushughulikia tatizo hili. Mifumo hiyo inategemea pairing tofauti za organic Rankine cycle, transcritical CO₂ Rankine cycle na closed Brayton cycle pamoja na vapor-compression, ejector au absorption refrigeration cycles. Comparison haikuzuiliwa kwenye kiasi cha umeme na ubaridi pekee; exergy efficiency, energy utilization factor, coefficient of performance ya ubaridi, radiator area, heat-exchanger area na volumetric flow rate katika turbine outlet pia zilitathminiwa.

Katika design point yenye thermal input ya 100 kW na equivalent heat-sink temperature ya 100 K, organic Rankine–vapor-compression refrigeration system inayotumia R600a ilitoa highest cooling-oriented performance kwa energy utilization factor ya asilimia 73,2 na coefficient of performance ya ubaridi 6,30. Organic Rankine–ejector refrigeration system ilifikia highest net electricity generation ya 18,9 kW pamoja na structure rahisi zaidi. Transcritical CO₂ Rankine–vapor-compression system ilitoa highest exergy efficiency ya asilimia 56,5.

Design-point results pekee hazikuamua final selection. Chini ya 90–325 K temperature variation wakati wa mchana wa Mwezi, energy utilization factor ya organic Rankine–vapor-compression system ilishuka hadi asilimia 37,3 katika high temperature. Katika ejector system, wakati equivalent heat-sink temperature ilizidi 309 K, ejector suction iliisha na cooling capacity ikashuka hadi zero. Transcritical CO₂ system, kwa kuongeza turbine inlet na outlet pressures pamoja, iliweza katika 325 K kudumisha energy utilization factor ya asilimia 58,5 na cooling capacity ya 47,5 kW. Kwa hiyo, study inachagua transcritical CO₂ Rankine–vapor-compression system kama technical route yenye robustness zaidi katika mchana wa Mwezi.

Results hazikutoka kwenye real lunar-base prototype, bali kwenye thermodynamic models na quasi-steady simulations. Heat losses, pressure drops, hardware transition dynamics, lunar dust, radiation damage na details za two-phase flow katika microgravity hazikuzingatiwa. Phase-change thermal-storage unit ilidhaniwa kuweka heat input constant katika 100 kW, lakini mass na capacity ya storage system hii hazikusiziwa separately.

Main problem ya research ni nini?

Kama energy generation na thermal control katika lunar base zitadesigniwa independently, matatizo mawili muhimu yanatokea. Kwanza, waste heat yenye usable temperature kutoka power cycle inatupwa directly angani na sehemu ya energy potential inapotea. Pili, refrigeration system inakuwa separate electrical load na kuongeza installed capacity inayohitajika kwa power-generation system.

Lengo la study hii ni kuhamisha mechanical work, pressure potential au waste heat kutoka power-generation cycle directly kwenda refrigeration cycle ili kutoa cascade energy utilization. Research ina main questions tatu:

• Ni power-generation–refrigeration pairing gani inayotoa highest performance katika design point chini ya lunar conditions?
• Kwa different coupling mechanisms, ni working fluid gani inayotoa best balance kati ya thermodynamic performance na hardware compactness?
• Mifumo iliyochaguliwa inaweza kudumisha cooling na electricity generation kwa kiwango gani wakati radiator-boundary temperature inapanda kutoka 90 K hadi 325 K katika lunar daytime?

Kwa nini mazingira ya Mwezi ni tofauti na energy systems za duniani?

High vacuum kwenye uso wa Mwezi inaondoa convective heat transfer. Waste heat inayozalishwa na system lazima itolewe hasa kupitia infrared radiation kuelekea deep space. Radiator area inaamuliwa kwa basic relation ifuatayo:

\[ A_{\mathrm{rad}}= \frac{Q_{\mathrm{rad}}} {\varepsilon\sigma \left(T_{\mathrm{rad,avg}}^{4}-T_{s}^{4}\right)} \]

• A_rad: Ni required radiator area na ina unit ya m².
• Q_rad: Ni heat ambayo radiator lazima itoe kwenda angani na ina unit ya kW.
• ε: Ni infrared emissivity ya radiator surface.
• σ: Ni Stefan–Boltzmann constant; 5,6704 × 10⁻⁸ W/(m²·K⁴).
• T_rad,avg: Ni average surface temperature ya radiator.
• T_s: Ni equivalent heat-sink temperature inayokabiliwa na radiator.

T_s inapoongezeka, difference T_rad,avg⁴ − T_s⁴ inapungua. Ili kutoa same amount ya heat, radiator area au radiator operating temperature lazima iongezwe. Kwa hiyo, lunar noon ndiyo most difficult operating condition kwa systems, si kwa sababu ya hot surface pekee, bali pia kwa sababu inapunguza net radiative capacity ya radiator.

Equivalent heat-sink temperature ilihesabiwaje?

Model inaunganisha infrared radiation kutoka lunar surface, direct solar radiation, solar light reflected kutoka lunar surface na deep-space background katika single equivalent temperature:

\[ T_{s}= \left[ F_{1}T_{m}^{4} + \frac{G_{s}}{\sigma} \frac{\alpha_{s}}{\varepsilon} \cos\theta_{1}(1+aF_{1}) + T_{\mathrm{space}}^{4} \right]^{1/4} \]

• F₁: Ni view factor ya radiator kuelekea lunar surface.
• T_m: Ni lunar-surface temperature.
• G_s: Ni solar constant katika lunar orbit; study imetumia 1367 W/m².
• α_s: Ni solar absorptivity ya radiator.
• θ₁: Ni solar zenith angle.
• a: Ni lunar-surface albedo; value ya 0,07 imetumika katika basic calculation.
• T_space: Ni deep-space background temperature.

Radiator ilichaguliwa kuwa horizontal surface inayoangalia deep space, kwa lengo la kupunguza view factor kuelekea lunar surface kadiri iwezekanavyo. Graph katika page ya 15 ya study inaonyesha kwamba katika synodic cycle ya Earth days 29,5, surface temperature inaongezeka approximately sinusoidally wakati wa daytime, kisha after Earth day ya 14,75 inashuka hadi approximately 90–100 K wakati wa lunar night.

Approximation iliyotumika kwa lunar-day surface temperature ni:

\[ T_{m}=90+ 275\sin^{0.55} \left(\frac{\pi D_{a}}{14.75}\right) \]

D_a ni lunar time katika units za Earth day. Katika off-design analysis, equivalent heat-sink temperature ya radiator iliwekwa 90 K around sunrise na sunset, na 325 K katika lunar noon.

Mifumo saba iliyounganishwa iliundwaje?

Katika page ya 10 ya study, Kielelezo 1 kinaonyesha flow diagrams za systems saba katika table moja. Systems zimegawanywa katika three different energy-coupling mechanisms.

Mechanical-shaft coupling inafanyaje kazi?

Katika Sys 1 na Sys 2, turbine ya power cycle na compressor ya vapor-compression refrigeration cycle ziko kwenye same mechanical shaft. Sehemu ya work inayozalishwa na turbine inahamishwa directly kwenda compressor; hivyo losses katika stages za electricity generation, motor na reconversion to mechanical work zinaepukwa.

Advantage ya coupling hii ni short energy-transfer path na high refrigeration performance. Disadvantage ni requirement ya matching turbine na compressor operating points chini ya same shaft speed na power balance. Kwa kuwa change katika radiator temperature inabadilisha turbine back pressure na compressor condensation pressure simultaneously, off-design control inakuwa critical.

Fluid–work-coupled ejector system inafanyaje kazi?

Katika Sys 3 na Sys 4, refrigeration cycle haitumii mechanical compressor. Sehemu ya high-pressure fluid ya power cycle inatumwa kwenye nozzle kama primary flow ya ejector. Pressure energy inabadilishwa kuwa velocity ndani ya nozzle na low-pressure region inatengenezwa. Region hii inasuck secondary refrigerant flow kutoka evaporator.

Ejector entrainment ratio inafafanuliwa kama:

\[ \mu=\frac{\dot m_{\mathrm{sf}}} {\dot m_{\mathrm{pf}}} \]

Hapa ṁ_sf ni mass flow rate ya entrained secondary flow na ṁ_pf ni mass flow rate ya primary flow.

Study imecalculate ejector kwa one-dimensional constant-pressure mixing model inayogawa ejector katika four regions: nozzle, suction chamber, mixing chamber na diffuser. Momenta za primary na secondary flows zinaungana katika mixing chamber, na velocity inabadilishwa kuwa pressure katika diffuser.

Absence ya moving parts inafanya ejector system ivutie kwa dusty lunar environment yenye limited maintenance opportunities. Hata hivyo, operation ya ejector inategemea certain primary-flow pressure na back-pressure ratio. Ratio hii inapopita critical limit, shock wave inasogea kuelekea nozzle na entrainment ya secondary flow inasimama.

Thermally coupled absorption systems zinafanyaje kazi?

Sys 5–7 zinatumia NH₃–H₂O absorption cycle badala ya compressor. Hot fluid kutoka power cycle inaingia kwanza kwenye generator ya absorption cycle na kusababisha ammonia kutenganishwa kutoka solution. Hivyo low-grade waste heat inatumika katika refrigeration production.

Approach hii inapunguza consumption ya high-grade electricity au shaft work na inaweza kuunganisha total heat load inayoenda radiator katika higher temperatures. Kwa upande mwingine, inahitaji generator, absorber, solution heat exchanger, rectifier, pump na additional piping. Area calculations za study zinaonyesha kwamba ingawa radiator inapungua, total heat-exchanger area inaongezeka significantly.

Thermodynamic components zilimodeliwaje?

Turbine power:

\[ W_{\mathrm{tur}}= \dot m_{\mathrm{tur}} (h_{\mathrm{tur,in}}-h_{\mathrm{tur,out}}) \]

compressor consumption:

\[ W_{\mathrm{com}}= \dot m_{\mathrm{com}} (h_{\mathrm{com,out}}-h_{\mathrm{com,in}}) \]

na pump consumption:

\[ W_{\mathrm{pump}}= \dot m_{\mathrm{pump}} (h_{\mathrm{pump,out}}-h_{\mathrm{pump,in}}) \]

zilihesabiwa. Turbine, compressor na pumps zilichukuliwa kuwa adiabatic; katika basic comparison isentropic efficiencies zao ziliwekwa 0,85.

Energy balance kwa heat exchanger ni:

\[ Q_{\mathrm{hex}} = \dot m_{h}(h_{h,\mathrm{in}}-h_{h,\mathrm{out}}) = \dot m_{l}(h_{l,\mathrm{out}}-h_{l,\mathrm{in}}) \]

Lower limit ilitumika kwa pinch-point temperature difference ili heat transfer ibaki physically possible. Katika general comparison 10 K ilitumika, huku some solution branches zikitumia minimum condition ya 5 K.

Main assumptions za model ni zipi?

• Kila operating point ilisolved kama steady state.
• Heat losses kwenda environment zilipuuzwa.
• Pipe na component pressure drops zilipuuzwa.
• Kinetic na potential energy changes, isipokuwa ejector nozzle, zilipuuzwa.
• Heat exchangers zilidhaniwa kuwa na sufficient na instantaneous heat transfer.
• Throttling valves zilichukuliwa kuwa isenthalpic.
• Isentropic efficiencies za turbine, compressor na pump ziliwekwa constant.
• Turbine expansion ilicalculateiwa kwa sections ili kuzuia wetness formation.
• Katika NH₃–H₂O cycle, ideal rectification ilidhaniwa na vapor kutoka generator ikalinganishwa na pure saturated ammonia.

Assumptions hizi zinafanya iwe rahisi kulinganisha system topologies katika common computational environment. Hata hivyo, pressure losses za real hardware, part-load efficiency changes, finite dynamics za heat exchangers na two-phase-flow instabilities haziko kwenye model.

Energy, exergy na compactness zilitathminiwa kwa indicators zipi?

Thermal efficiency

\[ \eta_{\mathrm{th}}= \frac{W_{\mathrm{net}}}{Q_{\mathrm{in}}} \]

Ni ratio ya net electricity generation kwa total thermal input.

Coefficient of performance ya refrigeration

Kwa vapor-compression cycle:

\[ COP_{\mathrm{VCR}}= \frac{Q_{\mathrm{cool}}}{W_{\mathrm{com}}} \]

kwa absorption cycle:

\[ COP_{\mathrm{AR}}= \frac{Q_{\mathrm{cool}}} {Q_{\mathrm{gen}}+W_{P}} \]

ilitumika. COP definition ya ejector cycle inategemea heat supplied kwa entire system. Kwa hiyo, COP values zilizotolewa kwa VCR, ERC na AR zinategemea different forms za driving energy; hazipaswi kusomwa kama ratios za same physical input moja kwa moja.

Exergy efficiency

\[ \eta_{\mathrm{ex}}= \frac{W_{\mathrm{net}}+Ex_{\mathrm{cool}}} {Ex_{\mathrm{in}}} \]

Inapima usable energy quality ya electricity na refrigeration pamoja. All refrigeration heat haichukuliwi kuwa na same quality kama electricity; exergy yake inayotegemea temperature level inatumika.

Energy utilization factor

\[ EUF= \frac{W_{\mathrm{net}}+Q_{\mathrm{cool}}} {Q_{\mathrm{in}}} \]

Inaonyesha kiasi gani cha total thermal input kinatumika kama electricity na useful refrigeration. EUF inapima energy quantity; haitenganishi energy quality kwa detail kama exergy efficiency.

Specific radiator area

\[ SRA= \frac{A_{\mathrm{rad}}} {W_{\mathrm{net}}+Q_{\mathrm{cool}}} \]

Ni radiator area inayohitajika kwa kila kW ya total useful output.

Specific heat-exchanger area

\[ SHEA= \frac{A_{\mathrm{hex,tot}}} {W_{\mathrm{net}}+Q_{\mathrm{cool}}} \]

Ina-ratio total area ya all heat exchangers katika system kwa useful output.

Turbine-outlet volumetric flow rate

\[ VFR=\dot m_{\mathrm{ORC,out}}v_{\mathrm{out}} \]

Ni product ya mass flow rate ya fluid katika turbine outlet na specific volume yake. Large VFR inahitaji wider final turbine stage, exhaust duct na pipe diameter.

Common design boundaries ni zipi?

Evaluation ya CO₂ cycles katika upper temperature ya 823 K na organic cycles katika 573 K ilitegemea thermal-stability limits za working fluids. Choice hii ina engineering meaning; lakini kwa kuwa systems hazikulinganishwa katika same upper temperature, allowed temperature level pia ina role katika exergy advantage ya high-temperature CO₂ cycles.

Six organic working fluids ziliscreeniwaje?

Kwa ORC-based systems, R245fa, R123, R1233zd, toluene, butane na R600a zilitathminiwa. Ilionekana kwamba same fluid haikuwa best katika coupling types zote, na separate selection criterion ikatumika kwa kila system.

Kwa nini R600a ilichaguliwa kwa ORC–VCR?

Katika ORC–VCR, main issue ni turbine-outlet volumetric flow rate na condensation pressure. Ingawa toluene ilifikia highest net power na low radiator area, katika 280 K ilitengeneza condensation pressure ya approximately 1,3 kPa na turbine-outlet volumetric flow rate ya 4500 L/s. Value hii ni approximately mara 80 ya R600a na inaongeza size ya turbine na exhaust line.

Butane ni thermodynamically slightly better kuliko R600a, lakini ina volumetric flow rate ya approximately 78 L/s na saturation pressure ya 105 kPa. R600a ilitoa approximately 55 L/s volumetric flow rate, positive pressure ya 185 kPa na cooling capacity only asilimia 3,2 lower kuliko butane. Kwa hiyo, R600a ilitambuliwa kama most balanced option kati ya thermodynamic performance na hardware compactness.

Kwa nini R1233zd ilichaguliwa kwa ORC–ERC?

Katika ejector system, si turbine performance ya fluid pekee iliyo muhimu, bali pia nozzle-exit velocity, speed of sound, shock losses na capacity ya ku-entrain secondary flow.

R123 ilifikia exergy efficiency ya asilimia 48,1, huku R1233zd ikifikia asilimia 47,3. Ingawa R123 ilitoa slightly more cooling na power, turbine-outlet volumetric flow rate yake ilikuwa asilimia 30,6 higher kuliko R1233zd. Favorable behavior ya R1233zd katika nozzle expansion na lower isentropic exponent yake zilitoa stable supersonic flow na better entrainment ratio. Kwa hiyo, more compact R1233zd ilichaguliwa kwa exchange ya small performance loss.

Kwa nini R1233zd ilichaguliwa kwa ORC–AR?

Ili absorption cycle iweze kutenganisha ammonia, ORC inahitaji kucondense around 370 K. Ingawa toluene ilizalisha high net power katika temperature hii, ilitengeneza condensation pressure ya approximately 67,5 kPa na volumetric flow rate ya 1170 L/s.

Butane ilifikia condensation pressure ya 2,25 MPa, huku R600a ikifikia 2,71 MPa, hivyo kuongeza required wall thickness ya pipes na heat exchangers. R1233zd ilitoa condensation pressure ya approximately 1,17 MPa, moderate volumetric flow rate na 7,8 kW more shaft power kuliko R245fa. Kwa hiyo, R1233zd pia ilichaguliwa kwa thermally coupled ORC–AR system.

Model ilivalidatiwaje?

Integrated structure ya all seven systems haikuthibitishwa kwa experiment. Badala yake, power na refrigeration submodels zililinganishwa na operating points za published independent calculations.

Validation graphs katika page ya 29 zinaonyesha current model ikifuatilia literature curves closely. Comparisons hizi zina-support kwamba basic thermodynamic equations zinatoa reasonable results. Hata hivyo, validation inahusu separate subsystems kutoka different sources; haivalidate all seven integrated configurations, lunar radiator na off-design control mechanism kwa pamoja.

Ni systems zipi zilijitokeza katika design point?

Katika equivalent heat-sink temperature ya 100 K na thermal input ya 100 kW, three different advantages zilitokea.

Sys 1: ORC–VCR

• Highest cooling capacity
• EUF: %73,2
• COP: 6,30
• Strong design point kwa missions ambapo life support na cabin cooling ni dominant

High latent heat ya R600a na low energy consumption ya liquid pump zilitoa strong performance katika low condensation temperature.

Sys 2: tRC–VCR

• Exergy efficiency: highest value ya %56,5
• Design-point EUF: approximately %65,2
• Relatively compact turbine na heat exchangers kutokana na high-density CO₂

Continuous change ya fluid temperature katika transcritical heat-addition process ilitengeneza better temperature match na heat-release curve ya solar collector na kupunguza exergy destruction.

Sys 3: ORC–ERC

• Net electric power: highest value ya 18,9 kW
• COP: only 0,52
• Simplest system structure
• Lowest specific heat-exchanger area

Kwa kuwa hakuna compressor, large portion ya turbine work inakuwa net electricity. Kwa upande mwingine, shock, mixing na momentum-transfer losses katika ejector zina-limit refrigeration performance.

Kwa nini absorption systems ziliondolewa?

Sys 5–7 zilitumia waste heat ya power cycle kupunguza specific radiator area hadi range ya 8,9–9,3 m²/kW. Kwa upande mwingine, specific total heat-exchanger areas ziliongezeka hadi 25,5–28,0 m²/kW kwa sababu ya generator, absorber, solution heat exchanger na rectifier.

Study ilitathmini kwamba licha ya lower radiator area, increase ya total heat-exchanger area inaweza kuwa unacceptable kwa mass na volume zinazopaswa kusafirishwa kwenda Mwezini. Sys 4 pia iliondolewa kwa sababu ya complex two-compressor structure na higher area requirement kuliko Sys 1–3.

Lunar-day off-design analysis ilifanywaje?

Lunar daytime iligawanywa kuwa many steady operating points katika process ya Earth days 14,8. Approach hii ni “quasi-steady” analysis: kila temperature point ilisolved kama independent steady state, na real transition dynamics zinazotokana na time-dependent temperature change hazikumodeliwa.

Phase-change thermal-storage unit ilidhaniwa kusmooth change katika solar radiation na kutoa constant 100 kW heat kwa power cycle katika entire daytime. Hivyo, change katika system performance ilidhaniwa kusababishwa mainly na increase ya T_s.

Kwa nini Sys 1 ilipoteza performance kubwa katika lunar noon?

R600a inafanya kazi katika saturated region below critical point. Katika region hii, condensation temperature na condensation pressure zimeunganishwa. T_s inapoongezeka, radiator temperature na R600a condensation pressure zinaongezeka rapidly.

Higher turbine outlet pressure:

• Inapunguza turbine pressure ratio.
• Inapunguza enthalpy drop inayopatikana kutoka turbine.
• Inaongeza pressure inayohitajika kwa compressor operation.
• Haiwezi kufidiwa kwa sababu turbine inlet temperature ime-limitwa na stability limit ya fluid.

Matokeo yake, EUF ya Sys 1 katika T_s = 100 K ilikuwa asilimia 73,2, huku katika 325 K ikishuka hadi asilimia 37,3. Study inatoa hii kama approximately asilimia 49 performance degradation.

Kwa nini cooling ya Sys 3 ilisimama kabisa?

Kadiri T_s inavyoongezeka, back pressure katika ejector outlet inaongezeka. Back-pressure ratio inapopita critical value, normal shock wave katika mixing chamber inasogea kuelekea nozzle throat. Low-pressure region inayovuta secondary flow kwenye nozzle exit inapotea.

T_s ilipozidi 309 K:

• Entrainment ya secondary refrigerant flow ilisimama.
• Cooling capacity ilishuka hadi zero.
• System iligeuka kuwa independent ORC inayozalisha weak electricity.
• EUF ilishuka hadi roughly asilimia 11,2.

Sys 3 pia haikuweza kuendesha ejector kwa thermal input chini ya 40 kW kwa sababu haikuweza kutengeneza sufficient primary-flow pressure.

Kwa nini Sys 2 ni robust zaidi?

Katika transcritical CO₂ cycle, temperature na pressure hazijaunganishwa rigidly kama kwenye saturation curve ya organic fluid. System inaweza kurekebisha turbine outlet pressure na, kupitia pump, turbine inlet pressure independently wakati radiator condition inabadilika.

Kwa kila T_s value, EUF ina maximum relative kwa turbine outlet pressure:

• Katika T_s = 150 K, optimum outlet pressure ni roughly 7,0 MPa.
• Katika T_s = 280 K, optimum outlet pressure inaongezeka hadi roughly 9,0 MPa.
• Katika T_s = 325 K, optimum outlet pressure ni roughly 11,2 MPa.

Katika low T_s condition, CO₂ iko katika high-density liquid-like state katika radiator outlet, na low outlet pressure ina-limit pump consumption. T_s inapoongezeka, CO₂ katika low pressure inakuwa gas-like, specific volume na pump consumption zinaongezeka. Kuongeza outlet pressure kunaongeza fluid density na ku-limit pump work.

Dual-pressure regulation mechanism ni nini?

Katika page ya 47 ya study, Kielelezo 16 kinaonyesha pressures mbili zikibadilishwa pamoja katika lunar daytime:

• Turbine inlet pressure inaongezeka kutoka roughly 19,5 MPa hadi 30 MPa.
• Turbine outlet pressure inaongezeka kutoka roughly 6,5 MPa hadi 11,2 MPa.

Kuongeza outlet pressure kunaongeza CO₂ density na kudhibiti pump consumption, huku kuongeza inlet pressure kukiongeza pressure potential before turbine. Hivyo, sehemu ya expansion ratio inayopotea kutokana na higher outlet pressure inarecoveriwa.

T_s inapoongezeka kutoka 90 K hadi 325 K:

Ingawa pump na compressor consumptions ziliongezeka significantly, increase katika turbine power ilifidia large part ya loads hizi. Kwa hiyo, net power na cooling haziku-collapse kabisa.

Ni system gani ni flexible zaidi wakati mission load inabadilika?

Study ilifafanua ratio ya cooling capacity kwa net electric power kama:

\[ CPR= \frac{Q_{\mathrm{cool}}} {W_{\mathrm{net}}} \]

Low CPR inaonyesha electricity-priority mission mode, huku high CPR ikiwa cooling-priority mission mode.

CPR range ya Sys 2, ikilinganishwa na Sys 1, ni approximately mara 1,9. Fixed nozzle geometry ya Sys 3 inaunganisha momentum transfer kati ya primary na entrained flow kwenye narrow operating point.

Ni findings zipi strongest za study?

• Inalinganisha seven integrated power–refrigeration topologies chini ya same lunar boundary conditions.
• Inaunganisha working-fluid selection si na cycle efficiency pekee, bali pia turbine volumetric flow, pressure na equipment area.
• Inaonyesha kwamba different fluid inahitajika kwa kila coupling mechanism.
• Inatathmini thermodynamic performance pamoja na radiator na heat-exchanger areas.
• Kwa kulinganisha subsystem models na published results, inaripoti deviations katika range ya asilimia 0,052–3,57.
• Inaonyesha kwamba ORC–VCR system inayoonekana superior katika design point inadhoofika significantly chini ya high T_s.
• Inaonyesha clearly physical operating limit ya ejector system above 309 K.
• Inaeleza dual-pressure regulation mechanism katika transcritical CO₂ system kwa pressure, power na cooling curves.
• Haichagui only most efficient system, bali system yenye robustness zaidi katika entire lunar daytime.

Main limitations za study ni zipi?

• Study ni preprint ambayo haijapitia peer review.
• Results hazijavalidatiwa kwa experimental prototype, hardware-loop test au lunar-mission data.
• Quasi-steady analysis haijumuishi real time-dependent dynamics za temperature na pressure transitions.
• Sensors, valves, actuators, delays na stability ya control algorithm hazijamodeliwa.
• Heat losses na pipe pressure drops zimepuuzwa.
• Isentropic efficiencies za turbine, compressor na pumps zimechukuliwa constant katika entire operating range.
• Heat exchangers zimedhaniwa kutoa instantaneous na sufficient heat transfer.
• Real hardware mass haijacalculatiwa; SRA na SHEA zimetumika kama area-based proxy indicators.
• Wall thickness, material density, turbine mass, pump mass, piping na structural supports hazijaconvertiwa kuwa total system mass.
• Phase-change thermal storage imedhaniwa kutoa constant 100 kW input katika entire daytime; storage material, capacity, efficiency na mass hazijasiziwa.
• Main off-design analysis ya study haijumuishi lunar night.
• Change ya radiator absorptivity na emissivity over time kutokana na lunar dust haijazingatiwa.
• Space radiation, fluid degradation, leakage, sealing na long-term material compatibility hazijachunguzwa.
• Separation ya two-phase flows katika low gravity, oil management na liquid distribution hazijamodeliwa kwa detail.
• One-dimensional constant-pressure mixing model imetumika kwa ejector; three-dimensional shock structure na viscous losses hazijasolved.
• Ideal rectification imedhaniwa katika NH₃–H₂O cycle.
• Haijaelezwa clearly thermodynamic properties zilitolewa kutoka software au database gani.
• Parameter uncertainty, sensitivity analysis au Monte Carlo uncertainty propagation haijatolewa.
• Kwa sababu COP definitions zinategemea different forms za driving energy, VCR, ERC na AR values si fully equivalent indicators.
• Maximum temperatures za ORC na CO₂ cycles ni tofauti; hali hii inaweza kuathiri exergy comparison.

Study ina-support nini?

• Ina-support kwamba lunar-base power na cooling systems zinaweza kufaidika kwa kudesigniwa ndani ya common energy chain.
• Inaonyesha kwamba katika low radiator-boundary temperature, ORC–VCR system inaweza kutoa high refrigeration performance.
• Inaonyesha kwamba ejector ORC system inaweza kuzalisha high net electricity ikiwa na few moving parts.
• Inaonyesha kwamba transcritical CO₂ cycle inafaa kwa active pressure regulation katika wide temperature range.
• Inaonyesha kwamba highest performance katika design point haimaanishi most robust design katika entire lunar daytime.
• Inaonyesha R600a kuwa more balanced option kwa mechanically coupled ORC–VCR, na R1233zd kwa ejector na thermally coupled ORC systems.
• Inaonyesha absorption systems zinaweza kupunguza radiator area huku zikiongeza total heat-exchanger area.
• Inatoa numerical results zinazoonyesha Sys 2 inaweza kutoa continuous electricity na refrigeration katika 90–325 K range.

Study haithibitishi nini?

• Haithibitishi kwamba tRC–VCR system itakuwa definitely na lowest total mass katika real lunar base.
• Haionyeshi kwamba proposed dual-pressure control itafanya kazi stably na reliably katika real hardware.
• Haithibitishi kwamba phase-change storage inaweza kutoa constant 100 kW heat katika lunar daytime kwa acceptable mass.
• Haionyeshi uninterrupted operation katika lunar night.
• Haionyeshi kwamba radiators zita-maintain same performance chini ya lunar dust, surface aging na micrometeorite effects.
• Haivalidate experimentally long-term space-environment safety ya R600a na R1233zd.
• Haionyeshi kwamba 309 K limit ya ejector ni invariant kwa all geometries na scales.
• Haionyeshi kwamba area indicators zinaequal directly real system mass au launch cost.
• Subsystem validations hazimaanishi integrated lunar-base system imevalidatiwa experimentally.

Scientific na engineering value kwa mtazamo wa Uturuki ni nini?

Study inatoa applicable methodological framework kwa research za space systems, thermodynamic cycles, radiative thermal control na small modular energy systems nchini Uturuki. Comparison approach iliyotengenezwa specifically kwa lunar base inaweza pia kuadaptishwa kwa high-altitude platforms, satellites, deep-space vehicles, polar research stations na off-grid energy–cooling systems.

Main methodological lesson ni kwamba kuchagua system based only on design-point efficiency haitoshi. Katika space hardware itakayotengenezwa nchini Uturuki, working fluid, part-load behavior, temperature limits, radiator area, equipment volume na control flexibility zinapaswa kutathminiwa ndani ya optimization moja.

Mbinu na Matokeo ya Utafiti

Research-method flow

Working-fluid selection results

Summary ya design-point comparison

Lunar-day off-design results

Final system selection

Chini ya evaluation criteria za study yenyewe, Sys 2, yaani system ambapo transcritical CO₂ Rankine cycle imecoupleiwa mechanically na vapor-compression refrigeration, ndiyo preferred configuration kwa lunar daytime.

Selection hii haitegemei highest EUF katika design point, bali combination ya features zifuatazo:

• continuous operation katika 90–325 K range,
• katika 325 K asilimia 58,5 EUF,
• maintenance ya 47,5 kW cooling capacity,
• mission-load regulation range ya 0,1–4,5,
• high exergy efficiency,
• hardware compactness kutokana na high density ya CO₂,
• ability ya kurekebisha turbine inlet na outlet pressures separately.

Result hii inapaswa kutathminiwa si kama definitive selection ya real lunar-base system, bali kama most suitable candidate ndani ya idealized thermodynamic boundaries na area-based compactness indicators za study.

Maelezo ya Chanzo na Mbinu

Jina kamili la asili la study:Configuration Selection and Lunar Daytime Off-design Evaluation of Power Generation-Refrigeration Coupled Systems for Lunar Bases

Waandishi na order: Zhijie Liu, Cong Wang, Lei Lang, Jiang Qin na Penghao Duan.

Equal first author: Equal contribution au equal-first-authorship information haijaelezwa.

Corresponding author: Cong Wang. Contact address katika study imetolewa kama congwang@hit.edu.cn.

Institutional affiliations:

• Zhijie Liu, Cong Wang na Lei Lang: School of Energy Science and Engineering, Harbin Institute of Technology, Harbin 150001, China.
• Jiang Qin: Harbin Institute of Technology; School of Power and Energy, Nanchang Hangkong University; Chongqing Research Institute, Harbin Institute of Technology.
• Penghao Duan: Department of Mechanical Engineering, University of Hong Kong, Hong Kong, China.

DOI:10.2139/ssrn.6985295.

Journal: Haijathibitishwa kwamba study imechapishwa katika peer-reviewed journal.

Publication platform: SSRN.

Original publisher: Hakuna final peer-reviewed publisher. SSRN record ni early-research/preprint platform record.

Publication year: 2026. Exact publication day haijaelezwa katika reviewed text.

Source type: Engineering preprint yenye thermodynamic system modeling, subsystem validation, working-fluid screening, parametric comparison na quasi-steady off-design analysis.

Peer-review status: Study haijapitia peer review. Kila page ina warning “Preprint not peer reviewed”.

Official publication link:SSRN study record.

Funding: Study inaripoti support ya project namba U2341276 kutoka YE Qisun’ Science Foundation na program namba 52406010 kutoka National Natural Science Foundation of China.

Maelezo haya ya Kituruki yameandaliwa kwa kuchunguza from beginning to end full text ya study, equations, system schematics, working-fluid tables, validation graphs, design-point comparisons, lunar-day performance curves, operating envelopes, dual-pressure-regulation results na references. Hakuna new scientific finding kutoka external sources iliyoongezwa kwenye results. External verification ilitumika only kucheck title, authors, DOI na SSRN record identity.

Study inategemea validated subsystem models na numerical simulations badala ya real hardware tests. Pressure drops, heat losses, transition dynamics, real control hardware, lunar dust, radiation, two-phase flow katika microgravity na mass ya phase-change storage hazijacalculatiwa. SRA na SHEA values si direct measurements za real system mass, bali area-based compactness indicators. Kwa hiyo, tRC–VCR result si final solution iliyovalidatiwa field katika lunar base, bali numerical candidate inayopendekezwa kupewa priority katika subsequent prototype na hardware-loop studies.