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1.
人工光植物工厂风机和空调协同降温节能效果 总被引：1，自引：2，他引：1
为减少人工光植物工厂中空调降温耗电量,该文利用风机引进外界低温空气与空调协同降温方式,以低功率的风机减少高功率空调的运行时间。结果表明,与仅利用空调进行降温的对照植物工厂相比,利用风机和空调协同降温的试验植物工厂节能效果明显,当植物工厂内部明、暗期空气温度分别设定在25℃和15℃,外界空气温度在-4～12℃时,明期耗电量的节省率为24.6%～63.0%,暗期为2.3%～33.6%,其节能效果随着外界空气温度的降低而增加;并且该降温方式可以将植物工厂内空气温度控制在目标值。因此,采用风机与空调协同方式对植物工厂内空气温度进行调控,可以减少植物工厂降温耗电量,降低其运行成本。 相似文献
2.
规模化猪场妊娠母猪舍改进湿帘降温系统的环境特性 总被引：2，自引：1，他引：2
为研究湿帘与地道结合的改进湿帘降温系统对妊娠母猪舍的环境特性,该研究采取现场测试的方法,选取河南地区某规模化母猪场妊娠舍为试验猪舍,对该猪舍夏季和冬季舍内热环境和空气质量环境进行测试和分析,结果表明：1）改进湿帘降温系统夏季对新风的平均降温功率增加了?84.4 kW,提高了25%的降温效果;冬季对新风的平均加热功率增加了121.6 kW且舍内无需供暖,87%以上的节能效果发生在地下风道前半程。2）试验猪舍舍内温湿度、风速分布均匀,且舍内温度波动低于3.7 ℃;综合猪舍母猪体感有效温度和呼吸频率等应激程度指标,母猪冬季处于舒适状态,夏季有轻度热应激状态现象。3）夏季和冬季舍内氨气（NH3）、二氧化碳（CO2）、和粉尘（PM2.5和PM10）的质量浓度分布均匀,且均小于国家标准规定的妊娠舍空气污染物浓度极限水平。综上所述,改进湿帘降温系统不仅降低妊娠母猪舍热环境调控的能耗并维持舍内空气质量环境良好,对建立环境友好型规模化母猪场具有积极意义。 相似文献
3.
太阳能辅助闭式热源塔热泵系统冬季制热性能 总被引：1，自引：1，他引：0
热源塔热泵系统以空气为冷热源,在冬季制热时其性能会随环境温度的降低而降低。为此研发了可应用陕南地区农村建筑的太阳能辅助闭式热源塔热泵系统,试验研究了冬季工况下系统的制热性能,初步分析了太阳热能与空气热能的互补机理。研究结果表明:系统制热量范围为12.1～15.2 k W,热泵机组性能系数范围为2.3～3.5,系统能效比范围为1.5～2.4,供热温度高于41℃;冷却水温度对压缩机耗电量的影响程度大于防冻溶液温度,冷却水平均温度每升高1℃,压缩要耗电量增加98.1 W,而防冻溶液平均温度每升高1℃,压缩机耗电量减小9.5 W;太阳能辅助热源塔热泵制热模式下,热泵机组通过改变防冻溶液与空气和集热工质换热温差的方法来改变防冻溶液从空气和集热水箱中的吸热量,以实现空气热能与太阳热能的互补。建议在实际应用中应避免供热温度过高以减小压缩机耗电;在集热水箱温度较高时通过降低风机频率减小风机耗电以提高系统综合能效,但应避免风机低频率工作可能给机组安全运行带来的隐患。 相似文献
4.
《Agricultural and Forest Meteorology》1987,40(2):163-176
The influence of pure water artificial fog on air and bud temperatures during night cooling under a clear sky is reported. Fog generation transforms the temperature profile near the ground into one which is nearly isothermal with height, compared to the normal inverted night temperature profile. The overall temperature reached is relatively constant and close to the wet bulb temperature of the air. Within the fog, the difference between air and bud temperature tends to 0.1–0.2°C, rather than to 0.5–2°C as outside the fog, depending on net radiation. The mechanisms whereby energy is transferred to buds to reduce air-bud temperature difference are discussed. Increases in incoming radiation and dew or frost deposits seem not to be high enough to reduce it in such a way. In addition, the dependence of fog stability on wind conditions is analysed. 相似文献
5.
《Biosystems Engineering》2003,84(3):315-329
A model for fan-ventilated greenhouse cooling is presented in which the primary heat transfer surfaces (cover/structure, canopy and floor) are represented as three parallel planes. Validation of the model was accomplished using data collected over 14 days. Agreement was good, with canopy temperatures over-predicted by only 0·1%, air temperatures in the canopy under-predicted by 0·5%, humidity of the canopy air under-predicted by 1·6% and transpiration rates under-predicted by 1·4%. Simulation runs suggest that when evaporative pad cooling is not used, little advantage is derived from increasing airflow rates beyond about 0·05 m3 m−2 s−1. When evaporative pad cooling is used, however, both air and canopy temperatures decline with increasing airflow rates up to 0·13 m3 m−2 s−1, the highest level considered. Increasing canopy size is predicted to be more influential in reducing air temperatures when evaporative pad cooling is used than when it is not, but its effect on canopy temperature is expected to be approximately the same whether or not evaporative pad cooling is used. With no evaporative pad cooling, the evapotranspiration coefficient (i.e., the ratio of energy used for transpiration to incoming solar energy) is predicted to range from 1·75 for an outside temperature of 36·8°C and an outside humidity ratios of 3·3 g kg−1 to 0·8 for an outside humidity ratio of 29·9 g kg−1 at the same temperature. With evaporative pad cooling, the coefficient is predicted to range from 0·6 to 0·8 at the same outside temperature and the same range of outside humidity ratios. 相似文献
6.
The water cooled system for controlling air temperature in photosynthesis assimilation chamber is cumbersome and requires a water tight system consisting of a double‐jacketed chamber. Manipulation of temperature control from one air temperature to another requires the adjustment of water bath temperatures. A simplified system for the air temperature control of the assimilation chamber and heat removal under high photon flux density would be desirable. An effective thermoelectric module cooling and heating system for a photosynthesis chamber was developed and evaluated for wheat (Triticum aestivum L.), sorghum [Sorghum bicolor (L.) Moench], and soybean [Glycine max (L.) Merr.] Air temperature variations within a chamber were maintained within 0.4°C, 0.9°C, and 0.3°C for the wheat, sorghum, and soybean chambers, respectively. The thermoelectric module system is simple and provides sufficient cooling and heating capacities to maintain chamber air temperature from 20°C to 30°C with 1100 μmol m‐2 s‐1 photon flux density for photosynthesis and dark respiration studies. Air temperature within a photosynthesis chamber during photosynthesis in plant nutrition studies is one of the important environmental parameters that must be controlled. Due to excessive heat under the relatively high photon flux density used in photosynthesis measurements, air temperature has been traditionally cooled and controlled by passing chilled water through double walled water‐jacket chambers3,5,7,8,12,13. Although the water cooled double‐jacket system has been successful in controlling temperature, maintaining water tight systems has been a problem. To alleviate some of the problems of a double‐jacketed system, air was cooled by passing over a water‐cooled radiator placed below the leaf4,11 . Under conditions of relatively high photon flux densities (1100 ymol m‐2 s‐1), water‐cooled systems do not provide sufficient cooling capacity to maintain 25°C or less air temperature. Mauney, et al.6 reported photosynthetic data obtained from cuvettes that were electrically cooled by the Peltier device, but no details of the system were provided. In later studies9,10,14, Peltier‐cooled systems appeared as a simple alternative to water‐cooled systems. This paper reports the details on an effective thermoelectric module cooling and heating system based on the Peltier principle for photosynthesis chambers. 相似文献
7.
Venlo型温室外遮阳和屋顶喷淋系统夏季降温效果 总被引：11，自引：4，他引：11
该文对荷兰Venlo型连栋温室夏季采用自然通风并结合遮阳网、室外屋顶喷淋的降温效果进行了实验研究。实验中对温室内空气温、湿度,太阳辐照度进行了测试,以比较外遮阳和屋顶喷淋的降温效果。结果表明:Venlo型温室夏季采用自然通风结合外遮阳和屋顶喷淋的降温措施后能够有效降低室内温度。不同于其它蒸发降温系统,屋顶喷淋没有造成温室内湿度的显著增加,室内的温度和湿度分布比较均匀。这种降温措施的能耗小,可以达到温室降温和降低温室夏季生产成本的双重目的 相似文献
8.
地道风降温系统利用地道周围的土壤作为冷源对空气进行降温处理，具有降温效果好、节省能源、使用寿命长、运行管理和维护简单等优点，并可兼用于畜禽舍冬季的加温。但该系统存在一次性建设投资较大的问题。文中提出和分析了改善地道风降温系统经济性的若干可行的途径。 相似文献
9.
Karin Kauer Henn Raave Tiina Köster Rein Viiralt Merrit Noormets Indrek Keres 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(3):224-234
Abstract In grassland areas where herbage production has no economic value, the cut grass is often left on the sward surface where its decomposition is influenced by weather conditions. Although the influence of temperature and humidity on decomposition has been investigated under controlled lab conditions, experimentation has generally been under ideal moisture conditions that have not tested the combinations of climatic limitations that might occur in the field. The decomposition of mown turfgrass clippings deposited at different times of vegetation period was studied in situ using nylon bags during the first 8 weeks after deposition to investigate the effect of weather conditions (the air temperature, relative humidity, precipitation) on decomposition. Decomposition is the highest in the case of high air humidity and temperature of 10°C. Limiting factors for decomposition at temperatures above 10°C is the air humidity and below 10°C the air temperature. The general tendency was that the rate of decomposition increased with increasing air temperature up to 10°C, but with further increases of air temperature the decomposition rate slowed down. Relative air humidity had a variable impact (at the beginning of the decomposition process (weeks 1–2) the influence was negative, during weeks 3–8 of the decomposition process the effect was positive), and hence had no generalized relationship with decomposition over the studied decomposition period (weeks 1–8). The most significant influence of weather conditions on the decomposition rate was recorded directly after cutting. If the cutting was done during hot weather conditions, the material was drying fast and therefore decomposed slowly. Our results indicate that for fast decomposition of clippings it is important to maintain the freshness of material. Lower decomposition rates occurred during conditions of hot and dry weather, and also cooler (temperature near to 0°C) weather, and can be compensated as soon as favourable weather arrives. 相似文献
10.
地下换热管土结构冻胀变形模拟 总被引：3，自引：3，他引：0
以地源热泵技术在农业节能领域中的应用为研究背景,针对地下换热管土结构冻胀变形问题开展数值模拟研究,基于孔隙增长率函数、冻土本构方程、含水量方程和相变传热理论建立数值模型,并结合试验验证该模型的有效性。利用模型对冻胀过程中岩土应力和管体变形特性进行分析,并考察管体降温速率（0.1、0.2、0.3℃/h）对上述2方面的影响。结果表明,岩土冻胀应力和管体变形程度均随冻结范围增大而增大,当冻结直径达到365 mm时,进水管流通面积减小约3.5%,出水管流通面积减小可超过4%,可见出水管的变形更为明显;冻结范围基本一致的情况下,换热管体缓慢降温可导致较大的岩土冻胀应力和出水管变形。 相似文献
11.
水墙封闭温室夏季降温特性 总被引：3，自引：3，他引：0
封闭温室(closed greenhouse)是一种建筑结构全封闭式的透光型温室,能够实现节能减排、室内蒸散水回收利用、维持高水平CO_2浓度以及隔绝气传病菌孢子等。但在夏季,封闭温室内高温环境难以有效控制,或需消耗巨大电能,无法投入生产。为降低夏季封闭温室内环境温度,从低碳节能的角度出发,设计并建造了一栋水墙封闭温室。2015年7月26日至9月10日,对水墙封闭温室夏季降温特性进行试验测试,结果表明:正午前后(10:00-16:00),室内平均气温为29.4~34.3℃,比室外低0.8~6.8℃,降温效果明显;且太阳辐射越强烈、环境温度越高,则水墙封闭温室的降温幅度越大(P0.01)。白天作物进行光合生产期间(06:00-18:00),封闭温室内气温有94.6%的时间被控制在35℃以内,可有效避免高温胁迫。夜间(18:00-06:00)室内湿度被控制在80%以下,平均湿度为54.7%~73.7%,比室外低7.2%~17.5%,降湿效果明显;且室内外湿度差与室内外温度差呈线性负相关(P0.01)。白天室内水平方向平均太阳辐射量为31.5~67.4 W/m~2,约为室外的11.9%~17.8%。太阳辐射由室外进入水墙封闭温室内,远红光占比由41.9%降低至9.2%,透过率仅为6.0%,有利于抑制室内高温。在室内太阳光谱中红、蓝光占比最大,分别为23.9%和27.1%,较之室外均有提升;其透过率分别为32.4%和37.5%,远高于紫外光和远红光。可见,水墙封闭温室可以有选择性的透过太阳光谱,抑制室内高温的同时保证充足的光合有效辐射。此外,墙体水温及室内气温分布、日变化均呈现一定规律。综上,水墙封闭温室能在夏季通过自身结构达到理想的降温效果,并获得适宜的湿度、光照等条件,是一种可行的、低碳节能的封闭温室型式,可为封闭温室的应用发展提供参考与技术支持。 相似文献
12.
《Agricultural and Forest Meteorology》1987,39(4):299-308
A survey was conducted in West Java to study the modification of the environment by traditional sheep and goat houses. The houses were all small and had a thick sloping roof with large overhangs, slatted walls and a slatted floor raised an average of 0.6 m above the ground. The mean wind speed outside the houses was low (0.3 m s−1) and on average the wind speed inside the houses was 37% of that outside. The mean temperature outside the houses was 21°C in the morning and 27°C in the afternoon. The corresponding relative humidities were 93 and 70%. The internal temperature was only 0.3°C higher than the external temperature on average and the internal humidity only 0.3 g m−3 higher than the external humidity, indicating that in general the houses were well designed to maintain the internal environment as cool and dry as possible. Comparisons between houses showed that a high internal wind speed, a low number of animals per unit area and a long roof overhang favoured a low internal temperature. Houses with higher platforms and more open walls had higher internal wind speeds than lower, more enclosed houses. Heat losses from the animals in the houses by long-wave radiation and evaporation were larger than the heat losses by convection. 相似文献
13.
为解决生菜应用营养液膜技术（nutrient film technique,NFT）在冬夏季根区温度控制的问题,该研究基于机器学习方法,结合温室内外历史环境数据,构建BP神经网络根区温度预测模型。为提高模型精度,采用蜣螂算法（dung beetle optimizer, DBO）优化BP神经网络模型的输入权重和阈值,构建了冬夏两个季节的基于DBO-BP神经网络的栽培槽内根区温度预测模型,并与GA-BP、BP神经网络模型进行对比。结果表明,根区温度预测值与真实值变化趋势较为一致,DBO-BP模型温度预测最大误差为2.21°C,决定系数为0.943,而GA-BP与BP模型决定系数分别为0.928、0.892;DBO-BP模型评价指标的均方根误差、平均绝对误差分别为0.707、0.549°C,均小于其他模型评价指标。DBO-BP神经网络可满足在NFT栽培中根区温度预测精度的需求,能够为生菜栽培根区快速控温提供有效方法。 相似文献
14.
The rate of popping of popcorn was measured in oil and in air. Kinetic data for lifetimes of individual kernels from a large population were obtained in oil at six constant temperatures (180–250°C) and also in an air‐popper at 202°C. The data are characterized by an induction period, which is, significantly, followed by a first‐order decrease in the number of unpopped kernels versus time. The activation energy for the first order process is 166.7 kJ/mol between 180 and 210°C, and 53.8 kJ/mol between 210 and 250°C. These data are consistent with a model that assumes 1) that the rate of heat transfer into a kernel follows Newton's law of cooling; 2) that in a sample of kernels there exists a distribution of critical pressures; 3) that for an individual kernel, the probability of popping is directly proportional to the difference between the internal aqueous vapor pressure and the kernel's critical pressure; and 4) that the measured rate constant at any temperature is an average overall of the kernels in the sample with critical pressures equal to or less than the internal aqueous vapor pressure. Minimum popping temperatures predicted by the model are 181 ± 2°C (oil) and 187 ± 2°C (air), in good agreement with previously reported direct measurements. 相似文献
15.
This study was designed to determine and compare root growth and nutritional responses of creeping bentgrass cultivars that differ in heat tolerance to differential, supraoptimal, shoot and root temperatures. Shoots and roots of ‘Penncross’ (heat sensitive) and ‘L‐93’ (heat tolerant) were exposed to four air/soil temperature regimes (20/20°C‐control, 20/35°C, 35/20°C, and 35/35°C) in water baths and growth chambers. Exposing roots to supraoptimal root temperature (35°C) while maintaining shoots at normal temperature (20°C) or particularly at 35°C reduced root fresh weight, root number, and contents of nitrogen (N), phosphorus (P), and potassium (K) in shoots and roots and accelerated root death for both cultivars. High root temperature had greater detrimental effects on root growth and nutrient element accumulation than high shoot temperature for both cultivars. A low root temperature at supraoptimal shoot temperature improved root growth, reduced root mortality; and increased N, P, and K contents in shoots and roots. Among the three nutrient elements, K was the most sensitive to changes in root temperature. L‐93 generally maintained higher fresh weight and number of roots and higher N, P, and K contents in shoots and roots, particularly K in roots, under high root (20/35°C) or shoot/root (35/35°C) temperatures. The results indicated that root growth and nutrient element accumulation, particularly of K, played an important role in creeping bentgrass tolerance to heat stress imposed on shoots by high air temperature or to roots by high soil temperatures. The enhanced root growth and nutrient element relations with a low root temperature at supraoptimal ambient temperatures could lead to the improved shoot growth in cool‐season grasses observed under these conditions. 相似文献
16.
Formation of ordered structures from disordered amylose is practically important. The thermal behavior of high-amylose maize starches was studied during cooling, following heating, and during subsequent reheating. Four commercial high-amylose genotype maize starches with varying amylose contents (ae du, ae su2, and ae [nominally both 50 and 70% amylose]) were heated to either 120, 140, 160, or 180°C, cooled to 5°C, and reheated to 180°C in a differential scanning calorimeter. Each starch was studied with its native lipid, as well as in reduced-lipid and lipid-free form. On cooling of lipid-containing starches, two distinct exotherms were observed and attributed to amylose-lipid complex formation and to amylose chain association. A distinct exotherm at ≈75°C was attributed to amylose-lipid complex formation. The exotherm attributed to amylose chain association on cooling varied according to the initial heat treatment, lipid level, and starch type. Starches with higher amylose contents showed larger exotherms on cooling. For initial heat treatments to 120 or 140°C, a broad exotherm beginning at ≈95°C was observed on cooling. In contrast, for initial heat treatments to 160 and 180°C, a sharper exotherm with a peak temperature below ≈55°C was observed. Upon reheating, samples that had been initially heated to 120 or 140°C showed a peak at >140°C that was attributed to the melting of ordered amylose. Starches initially heated to 160 or 180°C did not show this peak. This work illustrates that initial heating temperature, as well as lipid content and amylose content, all affect amylose chain association during cooling. Thus, this work suggests strategies for controlling ordering of amylose during processing. 相似文献
17.
Chao Ding Ragab Khir Zhongli Pan Jianyou Zhang Kang Tu Hamed El‐Mashad 《Cereal Chemistry》2015,92(5):441-448
The objective of this study was to investigate the effect of infrared (IR) drying followed by tempering and natural cooling on the change of physicochemical characteristics of white rice during up to 10 months of storage. The physicochemical characteristics of IR‐dried rice were also compared with those of conventionally dried rice. It took only 58 s to heat the rough rice from room temperature to 60°C with IR, and 2.17 percentage points of moisture was removed. After four months of storage, the increases in yellowness index, water uptake ratio, and volume expansion ratio of the rice dried with IR were 73.8, 63.9, and 55.3% those of rice dried with an ambient air drying method, respectively. IR drying slightly decreased the gelatinization temperature, enthalpy, and viscosities, reduced the changes in microstructure, and maintained cooking characteristics during storage. Therefore, the IR drying process is recommended to maintain the quality of white rice during storage. 相似文献
18.
Whether or not fruit buds in orchards can be protected from freezing by the use of fans, when no temperature inversion exists, depends upon the degree of bud radiant cooling at such times. Nighttime bud cooling in apple and peach orchards was estimated by comparing the temperature of buds and the adjacent air. The extent of radiant cooling was usually less than 0.6°C below ambient. Even this modest degree of radiant bud cooling appeared to require conditions with less than 60% cloud cover and wind speed less than 1 to 1.5 m s?1 at a height of 2 m. However, such conditions were also accompanied by inversions. The protective potential of fans in the absence of an inversion (postulated on the basis of bud radiant cooling) is therefore disclaimed on two accounts: (1) that the bud/air temperature difference is quite small and would only rarely span the bud critical temperature, and (2) that bud cooling would probably not occur during conditions which prevent the presence of an inversion. 相似文献
19.
两种风向下单栋塑料大棚内自然通风流场模拟 总被引：4，自引：0，他引：4
为分析塑料大棚的侧窗和山墙门对单栋塑料大棚内自然通风的影响，该文运用CFX流体动力学分析软件对简易单栋塑料大棚内的自然通风情况进行了三维稳态模拟。外界风向分别取平行于大棚屋脊和与屋脊夹角15°两种情况。模拟结果显示：当风向与屋脊平行时，室内流场在稳定状态时基本上沿屋脊的中心纵截面对称，室外气流从山墙门和两边侧窗的前半部分进入大棚内，从后半部分的侧窗处流出，气流在大棚中心地带的流速较高，而在侧窗附近流速较低。大棚顶部和后部气流变化比较复杂；在风向与屋脊成15°夹角情况下，室外气流从侧窗的迎风处、背风侧窗的前部和山墙门进入，从背风侧窗处流出，室内气流场有一个明显的偏转过程。从侧窗流入的气流和山墙门流入的气流相遇后在大棚内形成了各种程度的涡流，使得大棚内气流分布较为复杂。室外风向对单栋塑料大棚内气流场的形态有明显影响。 相似文献
20.
分析了数据中心机房主要耗能构成,得出要打造绿色节能机房必须降低机房的能源消耗大户空调和IT设备的能源消耗。在扬州市政府数据中心设计和实施建设过程中,针对机房制冷排热和IT设备选型部署,采取了多种绿色节能措施和手段。在降低机房制冷能耗方面,提出采用精确送风的封闭热通道技术将机房内冷、热气流分离,使热空气不在机房停留。同时,在空调外机加装雾化喷淋技术来降低空调能源消耗。在服务器选型及部署上,采用高性能、低功耗的服务器并运用虚拟化和云计算技术打造了一个绿色节能的数据中心机房。 相似文献