Heat Leak Research Articles

Time dependent model to analyze the magnetic refrigeration performance of gadolinium near the room temperature

Abstract A practical time-dependent model has been constructed to forecast the effectiveness and productivity of a magnetic regenerative refrigerator, as well as to assess its cycle efficiency. The model incorporates many irreversible factors, including the cycle frequency, heat transfer efficiency, and heat leak. Furthermore, it is utilized to scrutinize a magnetic refrigerator that employs spherical Gd particles as the magnetic substance and water as the heat transfer medium. The different cycle steps of the magnetic refrigerator are examined, while the cooling capacity and temperature differential between the two heat exchangers are appraised. The results also show that the magnetic refrigerator can obtain a temperature span of 5 K under 0.8 T magnetic field after 30 cycles in a particular situation. The findings provide valuable information for the future planning and advancement of magnetic refrigeration technology at room temperature.

All‐Climate Thermal Management Performance of Power Batteries Based on Double‐Layer Flexible Phase Change Materials

AbstractThermal management systems for power batteries based on phase change materials (PCM) are limited by low heat transfer efficiency, leakage issues, and high rigidity, and most of them cannot meet the needs of all‐climate thermal management. A double‐layer flexible phase change material (FPCM) sleeve structure for all‐climate thermal management is proposed in this study for the first time. Innovations in both material and design have enhanced the adaptability of the thermal management system. The outer layer FPCM achieves high thermal conductivity (4.23 W m−1 K−1) and electrical conductivity (0.95 S m−1), the inner layer FPCM achieves insulation (22.76 MΩ) and flexibility, the thermal contact resistance (TCR) between the double‐layer sleeve structure and the battery are measured to be only 0.15 °C W−1, significantly improved thermal management performance. Experimental results show that at 30 °C ambient temperature, 5 C discharge, the system reduces the maximum temperature by 14.5 °C, from 61.4 to 46.9 °C, compared to natural convection. Additionally, during heating, the system achieves heating rates of 7.0, 8.3, and 8.7 °C min−1 at −20, −10, and 0 °C, respectively, extending battery discharge duration by 32.5%, 65.9%, and 33.6%.

A hybrid experimental configuration for emissivity measurement at cryogenic temperatures

Abstract In cryogenic and high vacuum systems, radiation mode of heat transfer is the primary source of energy interaction owing to the wide temperature differentials and very low temperatures and pressures. Measurement of radiative properties such as emissivity is crucial in the design of cryogenic systems. Emissivity measurement at cryogenic temperatures requires careful consideration of the sample preparation and measurement conditions to ensure accuracy and reliability. Most experimental techniques developed so far are complex in their design and equipment, and they work only on a single measuring method. To address these challenges, this research has proposed a simpler and hybrid experimental setup that could employ both calorimetric and heat flux methods to directly measure the total hemispherical emissivity in the range 90 K–180 K. Experiments were conducted with five types of materials (black paint, stainless steel, aluminum foil, aluminized mylar foil, and copper sheet) by using both methods, and the results were validated with the literature data. The data obtained by calorimetric and heat flux methods for each sample showed a high level of consistency with each other, with a variation of only ±1.5%. Moreover, the discrepancy between the measured and literature data was within the acceptable range of 0.3%–10%. The total hemispherical emissivity of mechanically treated copper was higher than that of chemically polished copper by 11%. This simplified setup has incorporated all possible means to minimize heat leakages into and from the cryostat while maintaining accuracy. The obtained data can be used to accurately estimate the radiation heat loads in cryopumps and other cryogenic systems that use similar components.

Investigation of heat leakage calculations and experiments for a wide-mouth liquid nitrogen tank

ABSTRACT With the continuous development of biomedicine, the long-term low-temperature storage of biological samples has become essential. In order to meet the demand for long-term storage of liquid nitrogen to keep samples safe, a study on the evaporated gas recycling storage of liquid nitrogen tanks will be carried out. This research utilizes new approach to accurately calculate the heat leakage of the liquid nitrogen tank. The experimental results show that the theoretical heat leakage is 6.16 W, and the actual heat leakage is 7.07 W. By incorporating the insulating plug, the actual heat leakage was reduced by 61.2%, decreasing to 2.74 W, and the calculated heat leakage is 2.47 W. The error margin in both cases was approximately 10%. Furthermore, in contrast to existing investigations, this experiment with the 8W@77K pulse tube cryocooler for recovering nitrogen is conducted under environmental pressure rather than overpressure, and it also takes into account the sensible heat issues caused by ambient pressure. The ratio of 1.81 W of sensible heat to 2.74 W of latent heat is 2:3, indicating that under ambient pressure conditions, the impact of sensible heat cannot be ignored. The key improvement methods are given to improve the success rate of the experiment. The research results provide a useful reference for the re-cycling and storage of liquid nitrogen.

Experimental and numerical investigations of a diffusion bonded flat-type loop heat pipe for passive thermal management

Previous diffusion bonded loop heat pipes have been researched due to the benefits of this manufacturing technique, which includes direct sealing and maintaining material properties. The previous single-material diffusion bonded loop heat pipes were made of copper, leading to a high heat leak due to high thermal conductivity, causing a reduction in efficiency. This research used a new approach that separated the evaporator from the loop heat pipe while using diffusion bonding to manufacture a loop heat pipe using two materials, copper and stainless steel. This separation allowed for lower thermal conductivity materials to be used to help reduce the heat leak. Two evaporators with different wicks were tested, one made of copper and the other made of polytetrafluoroethylene. Both designs were tested in multiple orientations and operated for a range of 15 W to 45 W with an evaporator to condenser thermal resistance ranging from 2.18 °C/W to 0.004 °C/W. Additionally, a numerical model was developed to predict the performance of both evaporators, with an average temperature difference ranging from 5.5 °C to 6.6 °C for all thermocouple locations. The heat leak ratio was analyzed using the model, and a heat leak ratio of 7.6% to 8.0% and 13.6% to 16.0% for the copper wick and polytetrafluoroethylene wick loop heat pipe was calculated, respectively. This research demonstrates that diffusion bonding copper with a lower thermal conductivity material and using low thermal conductivity sealing material can help reduce the heat leak within diffusion bonded loop heat pipes.

Steady Heat Transfer Analysis of the Refrigerator Seal Considering Rigid and Flexible Contact

The rigid and flexible contact of the refrigerator seal has a significant impact on its heat transfer characteristics, but existing research has ignored this important factor. In this paper, the assembly physical model at the seal region is established by static structural analysis. Then a three-dimensional heat transfer numerical simulation is carried out. The assembly distance affects the contact state of the seal by changing the contact position between the seal and the door or the cabinet. The calculation results show that the calculated temperature at the seal region considering the actual assembly deformation is closer to the measured temperatures. In the case study, the heat leakage load decreases by 18.57% and 19.99% at the compressed state, while it increases by 4.45% under the stretching state. The proportion of heat transfer load in the path of rubber strip-cold air and rubber strip-outer shell of the cabinet is the largest, reaching over 30.0%. The heat transfer load of the cold bridge also accounts for over 20.0%. When optimizing the seal structure, reducing the contact interface length of rubber strip-cold air, reducing thermal conductivity, and increasing the contact thermal resistance of cold bridge should be focused on.

Analysis of the Use of Energy Storage in the Form of Concrete Slabs as a Method for Sustainable Energy Management in a System with Active Thermal Insulation and Solar Collectors

One effective approach to reducing the energy required for heating buildings is the use of active thermal insulation (ATI). This method involves delivering low-temperature heat to the exterior walls through a network of pipes carrying water. For ATI to be cost-effective, the energy supply must be affordable and is typically derived from geothermal or solar sources. Solar energy, in particular, requires thermal energy storage (TES) to manage the gap between summer and the heating season. A building that integrates various renewable energy systems and heating/cooling technologies should be managed efficiently and sustainably. The proper integration of these systems with smart management strategies can significantly lower a building’s carbon footprint and operational costs. This study analyzes the use of concrete slabs as a method for sustainable energy management in a system incorporating active thermal insulation and solar collectors. Using ambient temperature and solar radiation data specific to Cracow, Poland, the simulations evaluate the feasibility of employing a concrete slab positioned beneath the building as a thermal storage tank. The results reveal some drawbacks of using concrete slabs, including high temperatures that negatively affect system efficiency. Increased temperatures lead to higher heat losses, and during summer, inadequate insulation can cause additional heat leakage into the building. The findings suggest that water may be a more effective alternative for thermal energy storage.

Precise Calorimetry of Small Metal Samples Using Noise Thermometry

AbstractWe describe a compact calorimeter that opens ultra-low-temperature heat capacity studies of small metal crystals in moderate magnetic fields. The performance is demonstrated on the canonical heavy fermion metal YbRh$$_{2}$$ 2 Si$$_{2}$$ 2 . Thermometry is provided by a fast current sensing noise thermometer. This single thermometer enables us to cover a wide temperature range of interest from 175 µK to 90 mK with temperature-independent relative precision. Temperatures are tied to the international temperature scale with a single-point calibration. A superconducting solenoid surrounding the cell provides the sample field for tuning its properties and operates a superconducting heat switch. Both adiabatic and relaxation calorimetry techniques, as well as magnetic field sweeps, are employed. The design of the calorimeter results in an addendum heat capacity which is negligible for the study reported. The keys to sample and thermometer thermalisation are the lack of dissipation in the temperature measurement and the steps taken to reduce the parasitic heat leak into the cell to the tens of fW level.

Numerical simulation and experimental verification of dynamic cooling and temperature control of the optical cavity in a CO2 isotope analyzer

Accurate measurement of CO2 generated from different emission sources is the basis for controlling CO2 emissions and mitigating global warming. With advantages of high accuracy and rapid response, isotope analyzers using spectroscopic techniques, particularly those using cavity ring-down spectroscopy, have been widely used for CO2 emissions monitoring. However, these analyzers often face challenges such as spectral interference from impurity gases and unstable temperature control within the optical cavity in isotope analyzers. To address these challenges, this paper proposes a low-temperature optical cavity scheme utilizing a split Stirling-type pulse tube cryocooler. Combining thermal boundary conditions with particle swarm optimization, a dynamic cooling and temperature control model of the optical cavity was established in MATLAB. The model subsequently analyzed the cooling process, temperature control, and stability of the optical cavity. After 120 h, the simulations showed that the central part of the optical cavity had cooled to 126.4 K with a heat leakage of 8.90 W, in agreement with the experimental results that stabilized at 126.8 K. The temperature fluctuations remained within 0.1 K/h while controlling an overall temperature of 170 K with a temperature difference of ± 5 K. Changes in the electrical input power of cryocooler had no influence on the temperature distribution. This advancement not only lowers the operating temperature of the optical cavity to minimize spectral interference but also enhances the precision and efficiency of temperature control.

Investigating Taconis oscillations in a U-shaped tube with hydrogen and helium

Taconis oscillations are thermally induced spontaneous excitations of acoustic modes in tubes subjected to large temperature gradients. Cryogenic systems that experience these excitations suffer from increased heat leak and vibrations. This heat leak may also increase boil-off in long-term storage vessels for liquid hydrogen. In this study, U-shaped closed-end tubes with a cold mid-section are experimentally investigated to quantify the oscillation characteristics for hydrogen- and helium-filled systems at various mean pressures, including supercritical hydrogen states. Experimental measurements of the temperature distribution along the tube and acoustic pressure amplitudes and frequencies are taken in constant- and variable-diameter configurations near the onset of oscillations. Thirty different conditions are recorded with mean pressures ranging from 126 kPa to 1127 kPa for helium and 161 kPa to 1816 kPa for hydrogen. A low-amplitude thermoacoustic model is applied to predict the cold temperature and frequency corresponding to the onset of Taconis oscillations. The findings of this study indicate that Taconis oscillations in systems with hydrogen occur at smaller temperature differences than in more traditional helium systems by approximately 10 K. Hydrogen in the constant-diameter configuration excited when cryogenic temperatures reached 35–40 K, whereas helium excited when cryogenic temperatures reached 20–30 K. Special tubing networks, such as wider segments in the warm portion, can drastically elevate the excitation cold temperature resulting in onset temperatures between 50–60 K for both fluids. Taconis oscillations are also found to exist in conditions when liquid hydrogen starts forming in the cold zone of the system, as well as in supercritical states. The presented measurements are useful for designing cryogenic hydrogen storage systems to control these oscillations.

Anisotropic and shape-stable sugarcane-based phase change composites in the application of solar thermal energy storage

The study of anisotropically thermal conductive phase change composites (PCCs) with shape-stability is of great importance to improve the intermittent issues in solar thermal utilization, while some drawbacks like the high cost, low thermal conductivity, and poor durability of current PCCs restrains their practical applications. Herein, a cheap and scalable biomass-based PCC containing carbonized sugarcane (CSC), polyethylene glycol (PEG), and graphene (GF) is proposed. The abundant vessels inside CSC result in a high PEG loading rate of 82.48 %. The naturally occurring anisotropic structure inside CSC can drive GF to be oriented along the lengthwise direction, which gives PCC a high thermal conductivity anisotropy degree of 1.45. The prominent anisotropy improves the lengthwise thermal diffusion and restrains the transverse heat leakage to the environment. Besides, the loaded GF can further enhance the light absorption of PCC to 98 %. As a result, the prepared PCC can achieve high solar-thermal energy storage efficiencies of 79.3–91.7 % with variable solar intensity from 1 to 2 suns. Meanwhile, good anti-leakage and durability performances promote the practical utilization of PCCs. The present work paves a promising road for manufacturing biomass-based anisotropic PCCs in efficient solar thermal energy storage.

The impact of the heat leakage through air gap on thermoelectric generator applied in engine waste heat recovery

Efforts to enhance the performance of thermoelectric generators (TEGs) in engine waste heat recovery have primarily focused on directly increasing energy conversion efficiency. Heat leakage can occur in many parts of a TEG. It is needed to develop a model to help researchers study this phenomenon and propose measures to reduce heat leakage. To address this gap, this study establishes and validates a computational fluid dynamic (CFD) and finite element (FE) coupled model based on a TEG prototype and its engine test bench. Unlike other models, this approach captures the intricate dynamics of heat propagation from the TEG via air gaps, encompassing conduction, convection, and radiation. Comprehensive analysis reveals that heat leakage accounts for approximately 11% of TEG power output loss. Ignoring the impact of heat leakage can lead to an overestimation of TEG power output. Key areas of heat leakage are identified, and numerical factors influencing this phenomenon are explored. Vertical TEG placement and optimal spacing between thermoelectric modules emerge as effective strategies for mitigating the impact of heat leakage on power output. Leveraging these insights, strategic thermoelectric module placement, vertical TEG orientation, and the application of thermal insulation materials to the heat exchanger are proposed as measures to enhance TEG power output by approximately 5%. The experimental and numerical results underscore the feasibility of optimizing TEGs from the perspective of heat leakage, a crucial aspect previously overlooked. These findings provide valuable insights for future TEG optimization endeavors, highlighting the importance of addressing heat leakage to maximize TEG performance.

Thermal conductivity enhancement of polyethylene glycol/NF composite as stabilized phase change materials for thermal energy storage

Polyethylene glycol (PEG) has the advantages of large latent heat of phase transition, a wide range of phase transition, and cheap price, but the application of PEG in the latent thermal energy storage (TES) systems is hindered due to its lower heat transfer rate and leakage. Porous metal foam has excellent thermal conductivity and high strength, which can effectively improve the problems of PEG. In this study, PEG/nickel foam (NF) composite phase change materials (PCM) were prepared by vacuum molten impregnation method using NF as substrate. It was found that PEG had good compatibility with NF, and the highest impregnation rate of PEG6000/NF reached 85.73 %. The thermal conductivity of PEG2000/NF can be increased to 1.58 1.58 W·m−1 K−1, nearly 4 times larger than that of pure PEG. The phase change temperature range of the composite PCM is 51–63 °C, and the phase change enthalpy is 67.8–126.3 J·g−1. Furthermore, the PEG/NF composite demonstrated outstanding photothermal conversion properties and high thermal stability, which can be widely used in the field of building temperature control and device heat dissipation.

Exploring variations in the weight, size and shape of liquid hydrogen tanks for zero-emission fuel-cell vessels

We report an exploration of liquid hydrogen (LH2) tank technology, determining if improving LH2 tank weight, multiplicity or shape enables more hydrogen to be stored on hydrogen vessels. The improvements investigated are well beyond the current LH2 technology state-of-the-art. The platform for this study is a monohull H2 Baseline research vessel powered 100% by hydrogen.Regarding weight reductions, we found that the research vessel does not benefit significantly from large weight reductions of the LH2 tanks. A 50% reduction in mass of the inner pressure vessel led to a 3.1% reduction in the total research vessel weight. Reducing the LH2 tank weight to the asymptotic limit of zero results in a 7.1% reduction in the overall research vessel weight. This maritime application, while benefitting from a reduction in LH2 tank weight, is not a strong driver for LH2 tank weight improvements.The two large LH2 tanks of the H2 Baseline Vessel can be replaced with a multitude of smaller LH2 tanks. In two Multiplicity design variants, the total amount of stored LH2 was ∼5–9% less than that of the H2 Baseline Vessel, which does not motivate conducting the needed R&D that would drive the technology to smaller high-performing LH2 tanks.We did find a significant benefit to improving the shape of LH2 tanks, towards prismatic tanks that would better match the vessel hullform. Considering a “Shape Variant” that included space-consuming features such as tank connection spaces, manifolding and ventilation, we found a 26% improvement in stored LH2 compared to the H2 Baseline Vessel. The large improvement in storage capacity could warrant further LH2 tank R&D that can enable high performing prismatic LH2 tanks, such as pressure vessel steel developments allowing for higher strength/ductility at 20 K, improved insulation systems, methods for efficiently building prismatic tanks with insulation systems fit for 20 K service and flare-less techniques for managing heat leak (venting).The results are reviewed considering the current regulatory restrictions as well as prevailing limitations in LH2 tank manufacturing.

Design, construction and testing of the prototype cryogenic circulation centrifugal pump for the high energy photon source

A cryogenic circulation pump (CCP) with the small flow rate and low heat leakage, which is thekeyequipment of the cooling system for the cryogenic permanent magnet undulator (CPMU)and synchrotron monochromator in High Energy Photon Source(HEPS), is developed according to the design parameters and operation experiences. The mechanic structure of the CCP including a motor at room temperature, an impeller and a volute in the cryogenic environment is designed, and numerical simulation on the rotating shaft and internal flows are performed to predict the mechanical and hydrodynamic performances of the pump. Meanwhile, the experimental investigation of the CCP is carried out in the liquid nitrogen (LN2) cryogenic system, and the hydrodynamic performances of the CCP are verified experimentally. The results are shown that the calculated performances of the CCP are in reasonable agreement with the experimental results, which indicates that the numerical calculation model of the CCP is more effective. Moreover, the deviations of pressure drop and efficiency between the calculation and measurement are analyzed in this paper.

Continuous Wave Mode Test of Conduction-Cooled Nb3Sn Radio Frequency Superconducting Cavities at Peking University

A liquid helium-free cryostat for radio frequency (RF) test of the superconducting cavity is designed and constructed. Gifford-Mcmahon (G-M) cryocoolers are used to provide cooling capacity, and the heat leakage at 4 K is less than 0.02 W. Vertical and horizontal tests of two Nb3Sn cavities are carried out in the cryostat with different surface treatments outside the cavities. Both of the cavities achieve stable continuous wave (CW) operation. A novel treatment, which cold-sprayed a 3.5 mm thick Cu layer onto the outside of the cavity, enables the maintenance of an average temperature of 5.5 K in the cavity at a RF loss of 10 W, implying that the thermal stability and uniformity of the cavity has been significantly improved. Through the synergistic control of four metal film resistors, a cooling rate of 0.06 K/min near 18 K is realized, and the cavity temperature gradient is reduced to 0.17 K/m, which effectively improves the RF performance of the cavity. The maximum Eacc of the cavity reaches 3.42 MV/m, and the Q0 is 1.1 × 109. An electromagnetic–thermal coupling simulation model for the superconducting cavity is established and is in good agreement with the experimental results. The simulation results show that the cavity with a Cu-spraying treatment and the thermal links of 5N Al can satisfy the Eacc of 10 MV/m under conduction cooling.

Effect of tilt angle and base plate design on the performance of a loop heat pipe driven by vapor–liquid injector

With the rapid development of microelectronics technology and the increasing heat flux of electronic devices, loop heat pipes have garnered significant attention for their highly efficient passive heat transfer performance. However, the heat transfer performance of conventional loop heat pipes is impaired by the heat leakage, and the maximum heat flux is unable to meet the heat dissipation requirement of high-heat-flux devices. To solve this problem, a loop heat pipe with a vapor-driven injector (LHPI) was previously proposed. However, only the heat transfer performance of the horizontally-placed LHPI had been investigated in the preliminary stage, and the effect of gravity on the heat transfer performance was not further discussed. Now in this paper, a 360° rotatable experimental bench is designed to investigate the influence of the tilt angle on the performance of LHPI. In addition, a capillary wick is integrally sintered with the trough baseplate and the microcolumn baseplate of the LHPI, respectively, to reduce the thermal resistance between them. The results show that the heat transfer performance of LHPI is significantly affected by its tilt angle. In the horizontal condition, LHPI exhibits the lowest baseplate temperature and thermal resistance, and the best heat transfer performance, which verifies its applications in engineering. Integral sintering increases the maximum thermal load from 300 W to 350 W under stable operation conditions of LHPI. The maximum thermal load of the integrated micro pin-finned baseplate reaches 500 W, which improves the heat dissipation effect by 42 % in heat dissipation compared to the trough baseplate under the same conditions., providing an improvement angle for the traditional LHP.

Design and Simulation of Adiabatic–Damping Dual–Function Strut for LH2 Storage Tank

In the process of the on–board transportation of liquid hydrogen storage and transportation tanks, apart from considering the support strength and adiabatic performance, it is imperative to take into account the vibration characteristics of the carrying platform. The present work introduces a versatile support structure comprising a damping module and a ball contact insulation structure, enabling effective isolation of external vibrations while simultaneously providing support and insulation. The first step involves describing the principle of a flexible support structure and designing the mechanical structure. Subsequently, a damping analysis is conducted based on dynamic theory to establish the relationship between the spring and damping. Finally, the structural parameters of the dual–function strut are determined, followed by simulation of heat transfer performance. The results demonstrate that the dual–function strut exhibits exceptional vibration damping performance by reducing the amplitude of external vibrations greater than 5 Hz to less than 6%. Moreover, owing to the compact linear diameter spring structure of the vibration damping module and its ball contact effect, the thermal resistance of the dual–function strut is significantly enhanced, resulting in a mere heat leakage of only 22 W/m2 in a single rod section.

Subsurface urban heat island in the city of Ekaterinburg

Research subject. The subsurface thermal field in the city of Ekaterinburg (subsurface urban heat island). Aim. To determine criteria for the anomaly of mean annual subsurface temperatures in Ekaterinburg; to identify patterns of spatial distribution of underground temperatures; to quantify the main factors forming an urban heat island and changes in the heat content of rocks using mathematical modeling. Materials and methods. The main experimental data were obtained during the annual cycle of geothermal studies in observational boreholes of Ekaterinburg (22 boreholes) and surrounding areas (10 boreholes in Degtyarskiy, Verkh-Sysertskiy, Gagarskiy districts). Statistical analysis and mathematical modeling describing the impact of climate, local temperature anomalies of ground surface, and groundwater filtration to the underground thermal field were used when interpreting the obtained data. Results. At a depth of 20 m, the mean annual temperatures being less than 5°C and more than 6°C should be considered as anomalous. The maximum intensity of the urban heat island in Ekaterinburg is confined to densely built-up central areas of the city. The highest temperatures (>10°C) at a depth of 20 m are observed in boreholes located near buildings or directly therein. Here, a rapid decrease in temperature with depth is typical. Moderate anomalies from 6°C to 10°C are observed far from buildings. Remoteness from the central regions apparently plays a more important role in the formation of temperature anomalies than the type of urban surfaces (asphalt, concrete, lawns). Background temperatures (less than 6°C) were recorded in boreholes located outside the Ring Road. An analysis of patterns in the attenuation of annual temperature variations with depth allowed an area with intense vertical filtration (up to 24 m/year) to be identified near the City Pond. The most significant changes in heat content in the range of 10–50 m are associated with heat leakage from the basements of buildings, equaling to (23–46) × 107 J/m2. However, this heat is only hundredths of a percent of the total energy consumption spent on heating. Conclusions. The subsurface urban heat island of a large Russian city has been characterized for the first time. The results obtained can be used when developing a strategy for megacities in changing climate conditions.

Optimal design of coolant jacket for cryogen transfer pipelines

AbstractCryogenic liquids such as liquid oxygen and liquid hydrogen are extensively used in many processes and manufacturing industries. In these industries, transferring cryogens via pipelines is a routine phenomenon. As the boiling points and latent heat of cryogens are low, excessive vaporization of these cryogens is innate. Therefore, ensuring that the cryogen reaches the utility in its liquid form is challenging. In the case of liquid hydrogen and liquid helium, the pipelines are jacketed with a high boiling cryogen like nitrogen. The idea is to dump most of the heat into cheap nitrogen to limit the loss of precious hydrogen or helium. From a heat inleak point, maximizing the amount of nitrogen in the jacket is advantageous by choosing large cross‐sectional areas. Also, larger flow cross sections would lower pressure drops and, therefore, lower pumping costs. However, such a choice would add to the mass of the pipeline. An increase in the mass of the pipeline increases the need for better structural support of the pipeline assembly. Therefore, the design of cryogen jackets for limiting heat inleak is a multi‐objective optimization problem. In this work, we model the heat leak into the hydrogen via the nitrogen jacket and the pressure drop of liquid nitrogen, and we find the mass of the pipeline assembly. Then, we optimize the design of nitrogen jackets fitted over hydrogen pipelines. We employ the evolutionary optimization technique, genetic algorithm (GA), to perform this optimization.cryogen; genetic algorithm; heat inleak; liquid hydrogen; optimization.