TOTAL HEAT EXCHANGING ELEMENT

Abstract

A total heat exchanging element which is obtained by bonding liners and flutes together and can keep excellent total heat exchange efficiency, wherein each of the liners contains a moisture absorbent in an amount of 1 to 10 g/m.sup.2and each of the flutes has a water contact angle 2 seconds after dropping of 60° to 120°.

Claims

1. A total heat exchanging element obtained by bonding liners and flutes together, wherein each of the liners contains a moisture absorbent in an amount of 1 to 10 g/m.sup.2 and each of the flutes has a water contact angle 2 seconds after dropping of 60° to 120°.

2. The total heat exchanging element according to claim 1, wherein the flute has an attenuation of the water contact angle 1 minute after dropping of 50° or less.

3. The total heat exchanging element according to claim 1, wherein the flute has a Stoeckigt sizing degree of 30 seconds or more.

4. The total heat exchanging element according to claim 1, wherein the flute contains a moisture absorbent.

5. The total heat exchanging element according to claim 2, wherein the flute contains a moisture absorbent.

6. The total heat exchanging element according to claim 3, wherein the flute contains a moisture absorbent.

Description

EXAMPLES

[0031] The following examples are provided for the purpose of further illustrating the present invention but are in no way to be taken as limiting. “%” and “parts” in examples mean “mass %” and “parts by mass”, respectively, unless other noted.

Example 1

[0032] After softwood bleached kraft pulp (NBKP) was dissociated to a concentration of 3%, 2.5 parts of aluminum sulfate and 0.15 part of an internal sizing agent were added to 100 parts of a pulp slurry which had been completely beaten by using a double disk refiner and a deluxe finer to prepare a paper material. Thereafter, a substrate sheet for liners having a weight of 40 g/m.sup.2 was manufactured with a fourdrinier papermaking machine by using the paper material. Further, 5.1 g/m.sup.2 of calcium chloride was contained as a moisture absorbent in the obtained substrate sheet by impregnation with a nip coater at a speed of 60 m/min and a nip pressure of 343 kPa and dried to ensure that the moisture content became 10% so as to obtain a liner for use in a total heat exchanging element.

[0033] Subsequently, after softwood bleached kraft pulp (NBKP) was dissociated to a concentration of 3%, 2.5 parts of aluminum sulfate, 0.5 part of an internal sizing agent and 1.5 parts of a paper strengthening agent were added to 100 parts of a pulp slurry which had been beaten by using a double disk refiner and a deluxe finer to prepare a paper material. After 0.8 part of starch and 0.8 part of a sizing agent were contained with a size press apparatus in both sides of a paper produced with a fourdrinier papermaking machine by using the paper material, machine calendaring was carried out to manufacture a substrate sheet for flutes having a weight of 60 g/m.sup.2. This substrate sheet for flutes was used as a flute directly. The water contact angle 2 seconds after dropping in the flute was 117°. The obtained liners and flutes were bonded together by using an adhesive to manufacture a total heat exchanging element having a length of 300 mm, a width of 300 mm, a height of 300 mm and a step height of 2.0 mm.

Example 2

[0034] A total heat exchanging element was manufactured in the same manner as in Example 1 except that 2.5 parts of aluminum sulfate, 0.5 part of an internal sizing agent and 1.0 part of a paper strengthening agent were added to 100 parts of a pulp slurry to prepare a paper material and 0.2 part of starch and 0.2 part of a sizing agent were contained in both sides of a paper made by papermaking with a size press apparatus in the production process of a flute.

Example 3

[0035] A total heat exchanging element was manufactured in the same manner as in Example 1 except that 2.5 parts of aluminum sulfate and 0.3 part of an internal sizing agent were added to 100 parts of a pulp slurry to prepare a paper material and starch and a sizing agent were not contained in both sides of a paper made by papermaking with a size press apparatus in the production process of a flute.

Example 4

[0036] A total heat exchanging element was manufactured in the same mariner as in Example 1 except that 2.5 parts of aluminum sulfate and 0.15 part of an internal sizing agent were added to 100 parts of a pulp slurry to prepare a paper material and starch and a sizing agent were not contained in both sides of a paper made by papermaking with a size press apparatus in the production process of a flute.

Example 5

[0037] A total heat exchanging element was manufactured in the same manner as in Example 3 except that 1.6 g/m.sup.2 of calcium chloride was contained as a moisture absorbent in the substrate sheet for flutes by impregnation with a nip coater at a speed of 60 m/min and a nip pressure of 343 kPa and dried to ensure that the moisture content became 10% so as to obtain a flute in the production process of a flute.

Example 6

[0038] A total heat exchanging element was manufactured in the same manner as in Example 5 except that 4.9 g/m.sup.2 of calcium chloride was contained as a moisture absorbent in the production process of a flute.

Example 7

[0039] A total heat exchanging element was manufactured in the same manner as in Example 5 except that 9.0 g/m.sup.2 of calcium chloride was contained as a moisture absorbent in the production process of a flute.

Example 8

[0040] A total heat exchanging element was manufactured in the same manner as in Example 2 except that 1.2 g/m.sup.2 of calcium chloride was contained as a moisture absorbent in the production process of a liner.

Example 9

[0041] A total heat exchanging element was manufactured in the same manner as in Example 2 except that 9.5 g/m.sup.2 of calcium chloride was contained as a moisture absorbent in the production process of a liner.

Example 10

[0042] A total heat exchanging element was manufactured in the same manner as in Example 9 except that 0.1 part of starch and 0.1 part of a sizing agent were contained with a size press apparatus in the production process of a flute.

Example 11

[0043] A total heat exchanging element was manufactured in the same manner as in. Example 9 except that 0.05 part of starch and 0.05 part of a sizing agent were contained with a size press apparatus in the production process of a flute.

Example 12

[0044] A total heat exchanging element was manufactured in the same manner as in Example 9 except that starch and a sizing agent were not contained with a size press apparatus in the production process of a flute.

Example 13

[0045] A total heat exchanging element was manufactured in the same manner as in Example 3 except that 0.1 part of starch and 0.1 part of a sizing agent were contained with a size press apparatus in the production process of a flute.

Example 14

[0046] A total heat exchanging element was manufactured in the same manner as in Example 4 except that 0.1 part of starch and 0.1 part of a sizing agent were contained with a size press apparatus in the production process of a flute.

Example 15

[0047] A total heat exchanging element was manufactured in the same manner as in Example 1 except that 0.5 part of starch and 0.5 part of a sizing agent were contained with a size press apparatus in the production process of a flute.

Example 16

[0048] A total heat exchanging element was manufactured in the same manner as in Example 1 except that 0.2 part of starch and 0.2 part of a sizing agent were contained with a size press apparatus in the production process of a flute.

Example 17

[0049] A total heat exchanging element was manufactured. in the same manner as in Example 4 except that 0.3 part of starch and 0.3 part of a sizing agent were contained with a size press apparatus in the production process of a flute.

Example 18

[0050] A total heat exchanging element was manufactured in the same manner as in Example 4 except that 0.6 part of starch and 0.6 part of a sizing agent were contained with a size press apparatus in the production process of a flute.

Comparative Example 1

[0051] A total heat exchanging element was manufactured in the same manner as in Example 1 except that 3.0 parts of aluminum sulfate, 1.0 part. of an internal sizing agent and 2.0 part of a paper strengthening agent were added to 100 parts of a pulp slurry to prepare a paper material and. 1.5 parts of starch and 1.5 parts of a sizing agent were contained in both sides of a paper made by papermaking with a size press apparatus in the production process of a flute.

Comparative Example 2

[0052] A total heat exchanging element was manufactured in the same manner as in Example 1 except that 1.5 parts of aluminum sulfate and 0.1 part of an internal sizing agent were added to 100 parts of a pulp slurry to prepare a paper material and starch and a sizing agent were not contained in both sides of a paper made by papermaking with a size press apparatus in the production process of a flute.

Comparative Example 3

[0053] A total heat exchanging element was manufactured in the same manner as in Example 2 except that 0.5 g/m.sup.2 of calcium chloride was contained as a moisture absorbent in the production process of a liner.

Comparative Example 4

[0054] A total heat exchanging element was manufactured in the same manner as in Example 2 except that 10.5 g/m.sup.2 of chloride was contained as a moisture absorbent in the production process of a liner.

[0055] All the total heat exchanging elements of Examples and Comparative Examples were evaluated by the following methods, and the evaluation results are shown in Tables 1 and 2.

Method of Determining the Amount of Calcium Chloride

[0056] The amount of calcium chloride in each liner and each flute shown in Table 1 was measured by using a sample for determination which was collected from the liner and flute of each total heat exchanging element. About 0.1 g of a sample was cut out carefully from a part to which the adhesive of the liner and flute of the total heat exchanging element was not adhered and used as the sample for determination. The accurate amount of each of the samples for determination was measured, immersed in 100 ml of super pure water and irradiated with ultrasonic waves for 60 minutes to extract calcium chloride as a moisture absorbent. Thereafter, calcium chloride was filtered with a 0.45 μm disk filter to obtain the content of a calcium ion with ICP-AFS (manufactured by Perkin Elmer) and determine the mass-based amount (g/g) of calcium chloride by collating it with a calibration curve drawn in advance. The amount (g/m.sup.2) of calcium chloride was calculated from the mass-based amount of calcium chloride and the weights of the liner and The flute.

Method of Evaluating Total Heat Exchange Efficiency of Total Heat Exchanging Element

[0057] The total heat exchange efficiency of each of the manufactured total heat exchanging elements (element size: 300 mm in length, 300 mm in width, 300 mm in height, 2.0 mm in step height) after manufacture and the total heat exchange efficiency of each total heat exchanging element after it had been operated under cooling conditions described in “Air to air heat exchanger” as a total heat exchanger specified in JIS B 8628:2003 at as air flow of 200 m.sup.3/hr for 30 days were measured. The evaluation criteria are given below.

[0058] ⊚ (Excellent): total heat exchange efficiency of 60% or more

[0059] ∘ (Good): total heat exchange efficiency of 55% or more and less than 60%

[0060] Δ (Average): heat exchange efficiency of 50% or more and less than 55%

[0061] X (Poor): heat exchange efficiency of less than 50%

TABLE-US-00001 TABLE 1 Content of Content of Initial total Total heat Contact Attenuation moisture moisture heat exchange exchange angle of of contact absorbent absorbent efficiency after efficiency flute angle of in liner in flute manufacture after 30 (°) flute (°) (g/m.sup.2) (g/m.sup.2) (%) Eva. days (%) Eva. Ex. 1  117  6 5.1 0.0 56 ◯ 55 ◯ Ex. 2  100  2 5.1 0.0 56 ◯ 55 ◯ Ex. 3   80 46 5.1 0.0 55 ◯ 52 Δ Ex. 4   62 49 5.1 0.0 56 ◯ 50 Δ Ex. 5   78 48 5.1 1.6 56 ◯ 53 Δ Ex. 6   70 52 5.1 4.9 56 ◯ 56 ◯ Ex. 7   61 58 5.1 9.0 56 ◯ 60 ⊚ Ex. 8  100  2 1.2 0.0 52 Δ 51 Δ Ex. 9  100  2 9.5 0.0 62 ⊚ 60 ⊚ Ex. 10  97  9 9.5 0.0 61 ⊚ 57 ◯ Ex. 11  98 31 9.5 0.0 60 ⊚ 55 ◯ Ex. 12  96 65 9.5 0.0 61 ⊚ 52 Δ Ex. 13  82  8 5.1 0.0 55 ◯ 55 ◯ Ex. 14  64 10 5.1 0.0 56 ◯ 55 ◯ C. Ex. 1 123  1 5.1 0.0 55 ◯ Eva. cancelled C. Ex. 2  55 48 5.1 0.0 56 ◯ 49 X C. Ex. 3 100  2 0.5 0.0 48 X 48 X C. Ex. 4 100  2 10.5  0.0 65 ⊚ Eva. cancelled Ex.: Example; C. Ex.: Comparative Example; Eva.: Evaluation

TABLE-US-00002 TABLE 2 Stoeckigt Content of Content of Initial total Total heat Contact size moisture moisture heat exchange exchange angle of degree absorbent absorbent efficiency after efficiency flute of flute in liner in flute manufacture after 30 (°) (sec.) (g/m.sup.2) (g/m.sup.2) (%) Eva. days (%) Eva. Ex. 1  117 80   5.1 0.0 56 ◯ 55 ◯ Ex. 2  100 4   5.1 0.0 56 ◯ 55 ◯ Ex. 3   80 2   5.1 0.0 55 ◯ 52 Δ Ex. 4   62 1   5.1 0.0 56 ◯ 50 Δ Ex. 5   78 2   5.1 1.6 56 ◯ 53 Δ Ex. 6   70 1   5.1 4.9 56 ◯ 56 ◯ Ex. 7   61 1   5.1 9.0 56 ◯ 60 ⊚ Ex. 8  100 4   1.2 0.0 52 Δ 51 Δ Ex. 9  100 4   9.5 0.0 62 ⊚ 60 ⊚ Ex. 15 115 32   5.1 0.0 56 ◯ 55 ◯ Ex. 16 116 11   5.1 0.0 56 ◯ 52 Δ Ex. 17  61 24   5.1 0.0 56 ◯ 52 Δ Ex. 18  60 38   5.1 0.0 56 ◯ 55 ◯ C. Ex. 1 123 67   5.1 0.0 55 ◯ Eva. cancelled C. Ex. 2  55 0.5 5.1 0.0 56 ◯ 49 X C. Ex. 3 100 4   0.5 0.0 48 X 48 X C. Ex. 4 100 4   10.5  0.0 65 ⊚ Eva. cancelled Ex.: Example; C. Ex.: Comparative Example; Eva.: Evaluation

[0062] It is understood from comparison between Examples 1 to 9 and Comparative Examples 1 to 4 that, out of the total heat exchanging elements manufactured by bonding the liners and the flutes together, the total heat exchanging elements of Examples 1 to 9 having a content of the moisture absorbent in the liner of 1 to 10 g/m.sup.2 and a water contact angle 2 seconds after dropping in the flute of 60° to 120° have excellent total heat exchange efficiency, hardly experience a drop in total heat exchange efficiency and can keep high total heat exchange efficiency. In the total heat exchanging element of Comparative Example 2 whose water contact angle 2 seconds after dropping in the flute is lower than the lower limit and the total heat exchanging element of Comparative Example 3 whose content of the moisture absorbent in the liner is lower than the lower limit, total heat exchange efficiency dropped. Since water dripping occurred in the total heat exchanging element of Comparative Example 4 whose content of the moisture absorbent in the liner is higher than the upper limit and air leakage occurred in the total heat exchanging element of Comparative Example 1, they could not be operated for 30 days and accordingly their evaluations were cancelled halfway although total heat exchange efficiency could be measured after the manufacture of the total heat exchanging elements.

[0063] It is understood from Examples 1 to 4 that the total heat exchanging elements are excellent because a drop in the total heat exchange efficiency of each of the total heat exchanging elements 30 days after manufacture becomes smaller as the water contact angle 2 seconds after dropping in the flute becomes larger as compared with the total heat exchanging element right after manufacture.

[0064] It is understood from Example 2 and Examples 8 and 9 that, as the content of the moisture absorbent in the liner becomes higher, total heat exchange efficiency becomes higher. It is also understood from Examples 3 and Examples 5 to 7 that when a moisture absorbent is contained in the flute, a drop in the total heat exchange efficiency of the total heat exchanging element after 30 days is small as compared with the total heat exchanging element right after manufacture, which proves that the total heat exchanging element is excellent.

[0065] It is understood from Examples 9 to 12 that the total heat exchanging elements (Examples 9 to 11) having an attenuation of the contact angle 1 minute after dropping in the flute of 50° or less are excellent as a drop in total heat exchange efficiency after 30 days is small as compared with the total heat exchanging elements right after manufacture. It is also understood that as the attenuation is smaller, total heat exchange efficiency more hardly drops. Further, it is understood from comparison between Example 3 and Example 13 and comparison between Example 4 and Example 14 that as the attenuation becomes smaller, total heat exchange efficiency more hardly drops.

[0066] It is also understood from comparison among Examples 1, 15 and 16 and comparison among Examples 4, 17 and 18 that the total heat exchanging elements after 30 days having a Stoeckigt sizing degree of the flute of 30 seconds or more experience a small drop in total heat exchange efficiency as compared with the total heat exchanging elements right after manufacture, which proves that they are excellent.

INDUSTRIAL FEASIBILITY

[0067] The total heat exchanging element of the present invention is used as the total heat exchanging element of a total heat exchanger which carries out the exchange of temperature (sensible heat) and humidity (latent heat) at the time of supplying fresh air and discharging foul indoor air.