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Fluid preheatingRelated Patent Categories: Heating Systems, Combined With Water HeaterFluid preheating description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20070181702, Fluid preheating. Brief Patent Description - Full Patent Description - Patent Application Claims
BACKGROUND ART [0001] 1. Field of the Invention [0002] The present invention relates to fluid preheating. [0003] 2. Discussion of the Background Art [0004] U.S. Pat. No. 5,238,557 describes an apparatus for controlling the temperature of a mobile phase in a fluid chromatographic system which comprises both an ingoing capillary connected to an inlet of a column and an outgoing capillary connected to an outlet of the column. A portion of the ingoing capillary and a portion of the outgoing capillary are arranged in thermal contact with each other to form a contact region wherein heat exchange can occur. In preferred embodiments, liquid leaving the column at an elevated temperature loses a portion of its heat, thus avoiding or at least substantially reducing the transfer of heat to the detector. At the same time, liquid flowing to the column is pre-heated by the liquid leaving the column so that the heating power required for bringing the mobile phase to the desired temperature is reduced as compared with prior art devices. [0005] European Patent Application EP 0716302 describes a method for thermally stabilizing two columns for liquid chromatography. The method comprises the following steps: operating the first column at a first temperature which is different from the operating temperature of the second column, and transferring the sample contained in the first column to the second column by operation of switching means arranged between the two columns. In an embodiment of the invention, the first column is a pre-column and the pre-column is operated, during an enrichment phase, at a first temperature lower than an operating temperature of the separation column, in order to maintain a sample at a first temperature. The sample contained in the pre-column is heated, after completion of the enrichment phase, to a second temperature higher than the operating temperature of the separation column, then the sample contained in the pre-column is transferred to the separation column and then the sample is cooled to the operating temperature of the separation column. SUMMARY OF THE INVENTION [0006] It is an object of the invention to provide an improved preheating of a fluid. [0007] A heating system according to embodiments of the present invention comprises a heating unit with a heating flow path. The heating unit is adapted to be operated at a first temperature and to provide a heat transfer between the heating unit and the fluid passing through the heating flow path, with the heat transfer not being sufficient for heating up the fluid passing through the heating flow path to the first temperature. [0008] The heating unit and the heating flow path are implemented in a way that the fluid passing through the heating flow path is not heated up to the temperature the heating unit itself is kept at. The heating unit is purposely designed such that the a mount of heat transferred from the heating unit to the fluid does not suffice for bringing the fluid to the temperature of the heating unit. For this reason, the temperature of the fluid appearing at the outlet of the heating flow path remains below the temperature the heating unit is kept at. [0009] In prior art solutions, it has always been tried to provide a "good" heat exchanger with heating capabilities that are sufficiently large for heating up the fluid to the heating unit's temperature. It has never been considered to purposely design a heating unit with insufficient heating capabilities. However, it has been found that, when preheating a fluid, insufficient heating might yield superior results. [0010] In a preferred embodiment of the invention, the heating system is used for preheating a fluid before the fluid is supplied to a separation system adapted for separating compounds of a fluid sample. The separation system might e.g. be used for acquiring a peak pattern indicating the composition of the fluid sample, with each of the peaks being related to a certain compound of the fluid sample. By utilizing a heating system according to an embodiment of the present invention, the precision of the separation process is improved. It has been verified experimentally that insufficient heating of the fluid supplied to a separation system leads to an improved quality of the acquired peak pattern. In particular, it has been found that the peak's heights are increased and the peak's half widths are reduced when employing a heating system according to an embodiment of the present invention. Insufficient heating improves the sensitivity of sample analysis. Even tiny amounts of a certain sample compound may be detected. [0011] According to a preferred embodiment, the temperature of the fluid obtained at the heating flow path's outlet is lower than the first temperature, which is the temperature the heating unit is kept at. Because of the insufficient heating capabilities of the heating unit, the fluid does not attain the first temperature when traveling through the heating flow path. [0012] A heating system according to an embodiment of the present invention may e.g. be realized by reducing the heating power of the heating unit. Additionally or alternatively, the length of the heating flow path may be reduced until the heat transfer from the heating unit to the fluid becomes sufficiently small. In order to further reduce the heat exchange between the heating unit and the fluid, the number of turns of the heating flow path may be reduced. Another possibility for reducing the heat transfer is to increase the velocity of the fluid passing through the heating unit. [0013] In a preferred embodiment, the temperature of the fluid at the heating unit's outlet depends on the thermal properties of the fluid. In particular, the temperature increase of the fluid travelling through the heating flow path might e.g. depend on the heat capacitance of the fluid, and on the fluid's thermal conductivity. For example, the higher the fluid's heat capacitance, the more heat will be required for increasing the temperature by one degree Celsius. In case of a fluid having a large heat capacitance like e.g. water, a given heat transfer will lead to a relatively small increase of the fluid's temperature. In case of an organic solvent like e.g. methanol or acetonitrile, a heat transfer of similar magnitude might cause a much larger increase of the fluid's temperature. [0014] In a further preferred embodiment, a variation of the fluid's composition gives rise to a corresponding temperature variation of the fluid at the outlet of the heating flow path. A variation of the fluid's composition induces a corresponding variation of the fluid's thermal properties. This variation of the fluid's thermal properties gives rise to a corresponding temperature variation of the fluid obtained at the outlet of the heating flow path. Hence, the temperature of the fluid at the heating flow path's outlet might e.g. float in accordance with the fluid's composition. [0015] In a preferred embodiment of the invention, the heating system is implemented as a two-stage heating system comprising a main heating unit with a main heating flow path and an auxiliary heating unit with an auxiliary heating flow path. The main heating unit is located upstream of the auxiliary heating unit, with the outlet of the main heating flow path being fluidically coupled with the inlet of the auxiliary heating flow path. The main heating unit is kept at a second temperature, whereas the auxiliary heating unit is kept at the first temperature, with the first temperature being higher than the second temperature. [0016] The main heating unit provides sufficient heating capabilities for heating up a fluid passing through the main heating flow path to the second temperature the main heating unit is kept at. In contrast, the auxiliary heating unit is a heating unit according to an embodiment of the present invention, which is purposely realized in a way that the heat transfer between the auxiliary heating unit and the fluid is not sufficient for bringing the fluid to the first temperature the auxiliary heating unit is kept at. The main heating unit is implemented as a conventional heating unit. Thus, the main heating unit provides a basic level of heating, and there are no temperature variations of the fluid at the main heating unit's outlet. The auxiliary h eating u nit receives the fluid at the second temperature and provides for some additional heating, with the heating capabilities of the auxiliary heating unit not being sufficient for heating up the fluid to the first temperature the auxiliary heating unit is kept at. [0017] By implementing a two-stage heating process, the advantages of a heating unit according to embodiments of the present invention may be utilized while providing for reliable overall heating. By utilizing a two-stage heating process, the quality of peak patterns acquired in a separation process may be improved. In particular, the heights of the peaks may be increased and/or the peaks' half widths may be reduced. [0018] In a preferred embodiment, the main heating unit is implemented such that the fluid passing through the main heating flow path is heated up to the second temperature. For example, the main heating flow path might be sufficiently long, and/or the heating power of the main heating unit may be sufficiently large for heating up the fluid passing through the main heating flow path to the second temperature. [0019] In a preferred embodiment, the heating system comprises a sample injection unit located between the main heating unit and the auxiliary heating unit, with the sample injection unit being adapted for injecting a fluid sample into the fluid passing through the heating system. In this embodiment, the fluid sample is not conveyed through the main heating unit. The fluid sample only has to pass through the auxiliary heating unit. As a consequence, the dispersion of a sample plug is kept small, the half width of the acquired peaks is reduced, and a peak pattern of improved resolution is obtained. [0020] According to a further preferred embodiment, the heating system further comprises a sample heating unit adapted for preheating the fluid sample before the fluid sample is provided to the sample injection unit. [0021] According to a further preferred embodiment, one or more of the heating flow paths are realized as heat transfer capillaries. The capillaries' inner diameter might e.g. lie in the range between 0.05 mm and 0.30 mm. [0022] According to a preferred embodiment, a heating unit may be made of at least one of the following materials: cast iron, cast copper, cast aluminium, cast bronze. Continue reading about Fluid preheating... Full patent description for Fluid preheating Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Fluid preheating patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Fluid preheating or other areas of interest. ### Previous Patent Application: Arrangement and method for automatically determined time constant for a control device Next Patent Application: System and method for producing and delivering vapor Industry Class: Heating systems ### FreshPatents.com Support Thank you for viewing the Fluid preheating patent info. 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