Intermediate Channel Research Articles

Experimental and numerical investigation of the influence of varying micro-channel width on flow and heat transfer uniformity

This study integrates experimental and numerical methods to investigate the heat transfer and flow characteristics of microchannel heat sinks with varying width distributions. Water is used as the working fluid and laminar flow model is applied for simulation. Specifically, ten different width distribution structures were designed, including uniform-width configurations and nine non-uniform-width structures (I to IX) with progressively refined intermediate channel widths. Numerical simulations were employed to analyze the flow and heat transfer behaviors, and experimental validations were conducted on both the uniform-width structure and structures II, IV, V, VI, and IX. Results indicate that in uniform-width channel structures, the pressure drop and mass flow rate in intermediate channels exceed those in side channels, resulting in uneven temperature distribution at the base. Conversely, refining the intermediate channel widths under constant total width promotes more uniform flow and wall temperature distributions. A Performance Evaluation Criterion for Non-uniform Channels (PECNC) was introduced to identify the optimal structure. Ultimately, structure VI, characterized by continuously refined intermediate widths, emerged as the optimal design for achieving uniform temperature distribution. A mathematical expression for calculating the optimal microchannel width distribution conducive to uniform temperature distribution was also established.

Heat transfer analysis of nanofluid flow with entropy generation in a corrugated heat exchanger channel partially filled with porous medium

AbstractHeat exchanger research is mainly exploited to develop and optimize new engineering systems with high thermal efficiency. Passive methods based on nanofluids, fins, wavy walls, and the porous medium are the most attractive ways to achieve this goal. This investigation focuses on heat transfer and entropy production in a nanofluid laminar flow inside a plate corrugated channel (PCC). The channel geometry comprises three sections, partially filled with a porous layer located at the intermediate corrugate channel section. The physical modeling is based on the laminar, two‐dimensional Darcy–Brinkman–Forchheimer formulation for nanofluid flow and the local thermal equilibrium model for the heat equation, including the viscous dissipation term. Numerical solutions were obtained using ANSYS Fluent software based on the finite volume technique and the appropriate meshed geometries. The numerical results are validated with theoretical, numerical, and experimental studies. The simulations are performed for CuO–water nanofluid and AISI 304 porous medium. The coupled effects of porous layer thickness (δ), Reynolds number (Re), and nanoparticle fraction (φ) on velocity, streamlines, isotherm contours, Nusselt number (Nu), and entropy generation (S) are analyzed and illustrated. The simulation results demonstrate that heat transfer enhancement in clear PCC can be achieved using a porous layer insert. For the porous thickness range of [0.1–0.6], the corresponding range of average Nusselt number increase is [35.7%–176.9%], and the average entropy generation is [105.4%–771.9%]. The effect of the Reynolds number is more important in a porous duct than in a clear one. For δ = 0.4 and φ = 5%, the increase of Re in the range of [200–500] induces an increase in average Nusselt number in the range of [80.9%–108.4%] and average entropy in [222.9%–309.1%] comparatively to clear PCC. The effect of φ is practically the same for porous and clear channels. For φ = 5%, the increase on average Nu is about 9%, and entropy generation is 5%. Accordingly, important improvements in heat transfer in PCC can be achieved through the combined effect of flow Reynolds number and porous layer thickness.

Discontinuous Transition in Electrolyte Flow through Charge-Patterned Nanochannels.

We investigate the flow of an electrolyte through a rigid nanochannel decorated with a surface charge pattern. Employing lattice Boltzmann and dissipative particle dynamics methods, as well as analytical theory, we show that the electrohydrodynamic coupling leads to two distinct flow regimes. The accompanying discontinuous transition between slow, ionic, and fast, Poiseuille flows is observed at intermediate ion concentrations, channel widths, and electrostatic coupling strengths. These findings indicate routes to design nanochannels containing a typical aqueous electrolyte that exhibit a digital on-off flux response, which could be useful for nanofluidics and ionotronic applications.

Crystallographic fragment-binding studies of the Mycobacterium tuberculosis trifunctional enzyme suggest binding pockets for the tails of the acyl-CoA substrates at its active sites and a potential substrate-channeling path between them.

The Mycobacterium tuberculosis trifunctional enzyme (MtTFE) is an α2β2 tetrameric enzyme in which the α-chain harbors the 2E-enoyl-CoA hydratase (ECH) and 3S-hydroxyacyl-CoA dehydrogenase (HAD) active sites, and the β-chain provides the 3-ketoacyl-CoA thiolase (KAT) active site. Linear, medium-chain and long-chain 2E-enoyl-CoA molecules are the preferred substrates of MtTFE. Previous crystallographic binding and modeling studies identified binding sites for the acyl-CoA substrates at the three active sites, as well as the NAD binding pocket at the HAD active site. These studies also identified three additional CoA binding sites on the surface of MtTFE that are different from the active sites. It has been proposed that one of these additional sites could be of functional relevance for the substrate channeling (by surface crawling) of reaction intermediates between the three active sites. Here, 226 fragments were screened in a crystallographic fragment-binding study of MtTFE crystals, resulting in the structures of 16 MtTFE-fragment complexes. Analysis of the 121 fragment-binding events shows that the ECH active site is the `binding hotspot' for the tested fragments, with 41 binding events. The mode of binding of the fragments bound at the active sites provides additional insight into how the long-chain acyl moiety of the substrates can be accommodated at their proposed binding pockets. In addition, the 20 fragment-binding events between the active sites identify potential transient binding sites of reaction intermediates relevant to the possible channeling of substrates between these active sites. These results provide a basis for further studies to understand the functional relevance of thelatter binding sites and to identify substrates for which channeling is crucial.

Investigation of vertex a1>>VP for hadronic tau decays

In the framework of U(3) symmetric quark model, triangular diagrams are calculated that describe the strongly interacting vertices a1>>rhopi and a1>>K*K. The divergences arising when considering quark loops are regularized by covariant cutoff parameter. Based on four-particle hadronic τ decays, the quark structure of the resonance with quantum numbers JPC=1++ was studied. Theoretical estimates of intermediate channels with the meson for the partial decay widths of tau>>pipipinu, tau>>KKpinu and tau>>KKetanu are obtained. Contributions from contact channels describing the direct production of 3pi, KKpi and KKeta mesons by τ lepton current are taken into account. The interference of contact and intermediate axial-vector channels in determining the integral decay widths is studied. The matrix elements of the processes are obtained in the leading approximation of 1/Nc expansion. It is shown that calculations on τ lepton mesonic decays confirm the quark-antiquark structure of the a1 meson and clarify the role of the intermediate non-strange axial-vector channel in determining the integral partial decay widths. The obtained results are compared with experimental data by BaBar and Belle collaborations at the BEPC II and KEK lepton colliders.

Dispersive determination of fourth generation quark masses

We determine the masses of the sequential fourth generation quarks b′ and t′ in the extension of the Standard Model by solving the dispersion relations associated with the mixing between the neutral states Qq¯ and Q¯q, with Q (q) being a heavy (light) quark. The box diagrams responsible for the mixing, which provide the perturbative inputs to the dispersion relations, involve multiple intermediate channels, i.e., the ut and ct channels, u (c, t) being an up (charm, top) quark, in the b′ case, and the db′, sb′, and bb′ ones, d (s, b) being a down (strange, bottom) quark, in the t′ case. The common solutions for the above channels lead to the masses mb′=(2.7±0.1) and mt′≈200 TeV unambiguously. We show that these superheavy quarks, forming bound states in a Yukawa potential, barely contribute to Higgs boson production via gluon fusion and decay to photon pairs and bypass current experimental constraints. The mass of the b¯′b′ ground state is estimated to be about 3.2 TeV. It is thus worthwhile to continue the search for b′ quarks or b¯′b′ resonances at the (high-luminosity) Large Hadron Collider. Published by the American Physical Society 2024

Passing Behavior of Oligonucleotides through a Stacked DNA Nanochannel with Featured Path Design.

DNA nanotechnology has emerged as a useful tool for constructing artificial channels penetrating the lipid bilayer. In this work, we introduce a stacked DNA origami nanochannel device characterized by a width-variable pathway, consisting of narrow entrance and exit channels coupled with a wide, modifiable lumen. This design modulates the translocation behavior of oligonucleotides, revealing distinct stages of signal patterns in the recorded current traces. The observed prolonged dwell times indicate oligonucleotide retention, specifically due to the transition from the wide lumen to the narrower exit channel, while variations in current recovery between events suggested intermediate channel states between conducting and blocking. Further, by incorporating sequence-specific overhangs within the channel lumen, we achieved unique asymmetric current profiles during ATP aptamer translocation events. Featured stages also highlighted the aptamer binding dynamics and ATP-induced release. The distinguished oligonucleotide passing behaviors afforded by the stacked DNA origami channel with interior decoration demonstrated the strategic and profitable attempts at DNA nanochannel engineering for nanodevice development and applications.

Experimental and computational (Chemical Kinetic + CFD) analyses of Self-Recuperative annular tubular porous burner for NH3/CH4 -air Non-Premixed combustion

Ammonia is now being explored as a potential gas turbine fuel because of its renewable and carbon-free nature. Ammonia combustion possesses various limitations, such as high NO emissions, low burning velocity, and high auto-ignition temperature. Moreover, dual-fuel combustion approaches can be used to mitigate these drawbacks. However, the limitations of available information about the resulting emissions are insufficient to encourage widespread adoption. In this work, an NH3/CH4-air fueled self-recuperative high aspect ratio annular tubular porous burner is developed for gas turbine power applications. In this burner, an annular zone surrounds the combustion chamber to preheat the incoming air, while two perforated discs are mounted between the combustor and annular zone for uniform distribution of air. Eight Zirconia foams (4 of 10 PPI and 4 of 20 PPI) are stacked at the upstream side of the combustor. Experimentally, air preheat temperature, combustor exit temperature, NO, and CO emissions are analyzed and measured for various ammonia addition (0–41 % by weight) percentages, equivalence ratio of 1.0, and heat inputs of 17 & 21 kW for 10 PPI and a combination of 10 and 20 PPI porous foams. A preheated air stream coming from the annular zone speeds up fuel dissociation and helps in stabilizing the flame on the upstream side of the combustor. Combustor exit temperatures are lower in sandwich cases of 10 + 20 PPI than the porous foams of 10 PPI. However, with porous foams of 10 PPI, the air preheat temperature is higher. The insertion of porous foams shows better recirculation of heat and stable combustion is observed for higher percentages of ammonia and higher thermal inputs. The OH radicals are distributed for larger areas inside the dumb combustor, while for porous combustion, it is distributed near the porous foams. The porous sandwich cases of 10 + 20 PPI shows higher combustion efficiency compared to 10 PPI and without porous cases. The chemical kinetic analysis shows that the HNO and HCO radicals act as the main intermediate channel for NO and CO production.

A biocatalytic cascade in enzyme/metal continuous-microflow microgel with stable intermediate channel for point-of-care biosensing

A fast and accurate method for ultrasensitive monitoring of substrate is significant for cascade molecular detection. Here, we synthesize a glucose oxidase (GOx) microgel with iron coordination (Fe/GOx microgel). The microgel is cross-linked by chitosan and iron ion coordination which construct a tubular structure. Powder X-ray diffraction and Brunauer-Emmett-Teller results confirm the tubular crystal structure with a high specific surface area is formed in the microgel. The tubular structure offers a stable channel for intermediate transport which ensures the stabilization for the intermediate transport, and high specific surface area enhances the interaction between substrates and catalysts. As a result, the sensitivity of the Fe/GOx microgel is 175.5 μA mM−1 cm−2 and the lowest detection limit is 4.42 μM. In addition, the nanoscale Fe/GOx microgel also has the characteristics of reusability and maintains its activity after five times of catalysis. The generation of free radicals during the catalytic process can be detected by light detection and electrochemical signal detection within different detection limits. Therefore, Fe/GOx microgel provides a new platform and catalyst for the precise detection of cascade catalysis.

How is agricultural water efficiency affected by the digital economy? Insights from China

Abstract With the continued advancement of digital technology, the digital economy will gradually become the primary economic form in the future, having a profound impact on a variety of industries, including agriculture. Agriculture is a major source of global water use, and efficient water use in agriculture is critical to coping with water scarcity and ensuring food security. This study used publicly available data from 30 Chinese provinces from 2006 to 2017 to estimate the relationship between the digital economy and agricultural water use efficiency using the systematic generalized method of moments technique. According to the findings, a 1% increase in the digital economy indicator is associated with a 0.053% increase in agricultural water use efficiency. In addition, the digital economy improves agricultural water usage efficiency through three mediating channels: structural effect, scale effect, and spillover effect. For the digital economy and agricultural water use efficiency to develop in tandem, the Chinese government should strive to strengthen the development of the digital economy and work on the intermediate channels demonstrated in this study.

Experimental Study on Ship Squat in Intermediate Channel

<div>The sinking and trimming of the hull in the channel would directly affect the handling and navigation safety of the ship. In view of the ship sinking, a series of empirical formulas to estimate the subsidence have been put forward for vessel in spacious shallow water areas. However, most of the equations are based on seagoing vessels. They are not suitable for inland ships with small scales, shallow drafts, and narrow navigation width. Till now, research on ship squat in intermediate channel has not yielded more practical results. Here, a generalized physical model is used to study the sinking of 500t class ships in restricted intermediate channel under different channel widths, water depths, and speeds. The main factors affecting the squat are analyzed, the empirical relation is compared with the measured squat. The <i>Barrass</i> equation is modified, and the calculation relation of the settlement suitable for inland river ships is proposed. The correlation coefficient <i>R</i><sup>2</sup> of the modified equation is 0.818, the standard error is 0.046, and the maximum error is 0.14 m, which can be used as a reference for inland waterway design research.</div>

The Effects of Low-Carbon Governance on Energy-Environmental Efficiency: Evidence from China’s Low-Carbon City Pilot Policy

ABSTRACT Energy-environmental efficiency directly relates to global climate change and sustainable development. The research applies a staggered DiD design to estimate the effects of low-carbon governance on energy-environmental efficiency via panel data of 284 cities in China. Results show that low-carbon governance significantly improves both unified energy-environmental efficiency and pure energy-environmental efficiency. Heterogeneity analysis reveals that low-carbon governance in central cities has no significant effect on energy-environmental efficiency, while that in peripheral cities can improve energy-environmental efficiency, which indirectly confirms the law of decreasing returns to scale. At the same time, low-carbon governance in both resource-based and non-resource-based cities improves energy-environmental efficiency. However, among resource-based cities, low-carbon governance in growth and mature cities facilitates energy-environmental efficiency, while this effect disappears in declining and regeneration cities. Mechanism tests suggest that low-carbon governance immediately improves energy-environmental efficiency through intensive energy use and carbon emission reduction channels. The intermediate effect channels are mainly driven by fiscal decentralization, industrial structure upgrading, industrial agglomeration, innovation, and marketization, where fiscal decentralization plays a dominant role.

Study of Navigable Flow Conditions in the Intermediate Channel of Decentralized Cascade Locks

In this study, the effects of the different conveyance modes of the intermediate channel in decentralized cascade locks on navigation flow conditions were investigated. A new hybrid numerical simulation method was established to evaluate navigable flow conditions in intermediate channels at different water conveyance modes. This hybrid numerical simulation method was reliably compared by physical modeling tests. We used the 33.73 m class high-head intermediate channel filled with water as a study case. The study used the maximum water surface slope and maximum flow velocity as evaluation indexes for navigable flow conditions. The results showed that the navigable flow conditions of the centralized water conveyance mode were worse compared to the decentralized water conveyance mode in the intermediate channel. Especially in the upstream region of the intermediate channel with a centralized outflow, the navigable flow conditions were exceptionally harsh. We recommend the decentralized outflow mode in the high-head intermediate channel. This study provides an effective numerical simulation method for optimizing the water conveyance mode of the high-head intermediate channel of decentralized cascade locks and saving project investment.

Ethnic inequality and public health.

We examine the association between ethnic inequality and various key health outcomes for a global set of developed and developing countries. Our results show that higher ethnic inequality is associated with a poor state of public health, such as higher child and maternal mortality, increased stillbirths and child stunting, and reduced life expectancy at birth. This set of effects is found to be predominant mainly in developing countries, and Sub-Saharan African countries. Results remain robust to the inclusion of various other measures of inequality, ethnic composition indices, geographic endowments, and other relevant controls. We argue that lower contraceptive usage and poor vaccination rates are potential mechanisms through which ethnic inequality affects health outcomes. Policies targeted at improving public health may need to focus more on these key intermediate channels in ethnic minority regions.

KV7 but not dual small and intermediate KCa channel openers inhibit the activation of colonic afferents by noxious stimuli.

In numerous subtypes of central and peripheral neurons, small and intermediate conductance Ca2+-activated K+ (SK and IK, respectively) channels are important regulators of neuronal excitability. Transcripts encoding SK channel subunits, as well as the closely related IK subunit, are coexpressed in the soma of colonic afferent neurons with receptors for the algogenic mediators ATP and bradykinin, P2X3 and B2, highlighting the potential utility of these channels as drug targets for the treatment of abdominal pain in gastrointestinal diseases such as irritable bowel syndrome. Despite this, pretreatment with the dual SK/IK channel opener SKA-31 had no effect on the colonic afferent response to ATP, bradykinin, or noxious ramp distention of the colon. Inhibition of SK or IK channels with apamin or TRAM-34, respectively, yielded no change in spontaneous baseline afferent activity, indicating these channels are not tonically active. In contrast to its lack of effect in electrophysiological experiments, comparable concentrations of SKA-31 abolished ongoing peristaltic activity in the colon ex vivo. Treatment with the KV7 channel opener retigabine blunted the colonic afferent response to all applied stimuli. Our data therefore highlight the potential utility of KV7, but not SK/IK, channel openers as analgesic agents for the treatment of abdominal pain.NEW & NOTEWORTHY Despite marked coexpression of small (Kcnn1, Kcnn2) and intermediate (Kcnn4) conductance calcium-activated potassium channel transcripts with P2X3 (P2rx3) or bradykinin B2 (Bdkrb2) receptors in colonic sensory neurons, pharmacological activation of these channels had no effect on the colonic afferent response to ATP, bradykinin or luminal distension of the colon. This is in contrast to the robust inhibitory effect of the KV7 channel opener, retigabine.

Computational modeling of a thread-based microfluidic fuel cell with carbon fiber electrodes

Thread-based microfluidic fuel cells are promising micro power sources for portable and wearable electronic devices. In this study, a three-dimensional computational model is developed for a thread-based microfluidic fuel cell with carbon fiber electrodes. The interaction of fluid flow, species transport and electrochemical reactions is elucidated. The cell polarization curve obtained from modeling is validated by the experimental data. Moreover, effects of operational parameters and structural parameters on the cell performance and mass transport are further investigated. Results demonstrate that the presence of the intermediate flow channel can effectively prevent the reactant crossover and the parasitic current density is negligible. Appropriate increase in the reactant concentration is beneficial to yield uniform concentration distribution and enhance the mass transfer. Besides, the peak power density is only increased by 0.7% when the flow rate of anolyte and catholyte is increased by four times. Additionally, lowering the electrode spacing and the electrode porosity result in the superior cell performance. With the electrode spacing of 3 mm and the electrode porosity of 0.6, the peak power density of 34.6 mW cm−2 and the maximum current density of 112.5 mA cm−2 are achieved. This work provides theoretical guidance for future development and optimization for thread-based microfluidic fuel cells.

Numerical and experimental investigations of the heat transfer and fatigue life of a new W-type mini microchannel heat exchanger

To solve the problems of heat dissipation and improve the reliability of high heat flux electronic devices, a new W-type mini microchannel heat exchanger is proposed. Firstly, the effect of the inlet and outlet positions on the flow and thermal behaviors are discussed. Secondly, two traditional heat sinks are introduced to compare the cooling ability with the new exchanger. The results shows that the temperature difference of W-type heat exchanger is 10.4 K, which is lower than that of the two traditional channels. Thirdly, the effect of width for the intermediate channel and inlet annular channel length on heat transfer characteristics are analyzed. The results indicate that when the width of the intermediate channel is 4 mm and the channel length is 15.5 mm, the temperature uniformity of the heat exchanger is the best with appropriate pressure drop. On this basis, the experimental test is carried out to verify the numerical results. It is found that the maximum Nusselt number and pressure drop errors between numerical and experimental tests are 8.01% and 5.06%, respectively, which verifies the correctness of the numerical results. In addition, the strength of the heat exchanger is checked, and the maximum working stress is 249.76 MPa indicating that the strength of the heat exchanger meets the using requirements. Finally, the influence of ambient temperature on the fatigue life of heat exchanger is analyzed. The results show that the fatigue life presents a trapezoidal trend with the change of ambient temperature. Moreover, the numerical correlation of fatigue life is achieved.

Taxing the rich but not the capitalists: Direct taxation in Sisi’s Egypt (2014-2021)

ABSTRACT How come authoritarian regimes target certain social constituencies with direct taxation more successfully than others? This article addresses the recent surge in Egypt’s property tax revenues since 2014, which has almost exclusively fallen on the shoulders of rich property-owners in urban areas. Conversely, similar efforts to collect capital gains taxes from investors in the stock market failed miserably during the same interval. What might explain such disparity between property-and capital-holders under Sisi’s rule? Invoking Albert Hirschman’s paradigm, I argue that rich property holders in urban areas could be pressed successfully for direct taxation because they lacked viable exit options given the immobile nature of their assets, the national scope of property taxes, underdeveloped financial system and the inflation-context. Even though they had a voice, it could be ignored with minimal political and economic repercussions for the ruling regime, given the lack of intermediate channels. Conversely, large and concentrated capital holders could utilize the more mobile nature of their assets to credibly threat exit, amid the regime’s desperate need for re-launching the economy. Moreover, they could voice their protest and coordinate collective economic action on sectoral or cross-sectoral basis without much need for intermediaries. Specific to Egypt, the contrast of both simultaneous processes of direct taxation might inform us of the class dynamics of the Sisi regime, which could adopt relatively progressive direct taxation in some areas like real-estate property despite the overwhelming regressive fiscal reforms while showing a terminally limited ability to effectively collect direct taxes on big capital holders.

The contribution of intermediate conductance calcium-dependent potassium channels to hypothalamic vasopressin neuronal excitability

Vasopressin (VP) magnocellular neurosecretory neurons of the supraoptic nucleus (SON) in the hypothalamus are critical regulators of renal water retention and vascular tone. VP neurons undergo detrimental plastic changes in cardiovascular diseases such as heart failure (HF), resulting in hyperexcitability and thus altered fluid/electrolyte balance. Hyperexcitability is caused in part by changes in intrinsic excitability mechanisms, including the slow afterhyperpolarization (sAHP), a phenomenon underlain by a calcium-dependent K+ current ( I sAHP). The sAHP is activated by Ca2+ and results in an efflux of K+ from the cell, hyperpolarizing it, and throttling firing. Importantly, we found that the sAHP is greatly inhibited in VP neurons from HF rats, contributing to increased neuronal excitability in this condition. While the features of the sAHP are well characterized, the identification of the channel underlying the I sAHP is unknown. Combining patch clamp electrophysiology and pharmacology in Wistar rats, we investigated Intermediate conductance Ca2+-dependent K+ (IK) channels as a potential candidate responsible for carrying the I sAHP. We generated and measured I sAHPs in voltage clamp via fixed steps of twenty spikes at twenty Hz and measured the the I sAHP as the resulting tail current at the end of the pulse. To account for rundown of the current over the recording period and for the pharmacological blocker’s slow mechanism of action, we measured I sAHPs every 60 seconds for at least 15 minutes. Bath application of TRAM-34 (2 μM) at 7 minutes, a specific IK channel blocker, failed to inhibit I sAHP peak amplitude or area (p > 0.05; n=36 SON neurons). We used biocytin-filled pipettes to identify neurons post hoc and run immunohistochemistry for oxytocin (OT) and VP to identify cell type within the SON. We found no significant difference in I sAHP amplitude or area between VP and OT cells under either control or TRAM-34 application. Taken together, our studies indicate that IK channels do not contribute to the I sAHP in SON neurosecretory neurons, despite robust IK expression in this region. Future studies will aim at identifying the role that IK channels play in SON, as well as targeting other potential K+ channel candidates for this NHLBI F32 HL158172 (MKK) NHLBI HL090948 (JES) NINDS NS094640 (JES) This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Uncovering the role of renewable energy innovation in China's low carbon transition: Evidence from total-factor carbon productivity

The rapid growth of Chinese renewable energy innovation has shown great potential to improve total-factor carbon productivity (TFCP), but it still lacks sufficient literature understanding of the detailed impact and mechanisms. This paper empirically tests the influence mechanism, effect characteristics, and causal configurations based on a sample of 30 provinces from 2006 to 2017. We reveal optimizing the energy structure is the crucial intermediate channel for renewable energy technology innovation improving the TFCP, but it is not the unique mechanism. Since renewable energy technology innovation could directly improve the efficiency of the full industrial chain of electricity, the remaining channel can be summarized as the power operating efficiency improvement. From the heterogeneous analysis, the technological innovations in wind and solar energy display relatively larger contributions to the growth of total-factor carbon productivity. The threshold effect analysis further indicates the larger the coal consumption, the larger probability for renewable energy innovation to play a role in improving TFCP. Eventually, we observed four causal configurations of renewable energy technology innovation to determine the TFCP. It suggests renewable energy innovation cannot affect TFCP independently and often acts with other factors, eventually explaining the actual levels of regional TFCP.