I’m looking for ideas for heating the propane tanks in my hot air balloon.
My hot air balloon feeds liquid, not gas, to the vaporizing coils of the burner. Heat loss from the balloon is about 1 million btu’s per hour. Our burners are rated for at least 12 million btu’s per hour. Burner output depends on fuel pressure. Propane fuel pressure is a function of fuel temperature. As fuel is burned off the pressure tends to drop and burner output drops. My burner requires a pressure of 60 to 140 psi. To achieve this pressure the fuel tanks need to be between 40 to 100 degrees F. Fuel temperature during winter flying can be an issue.
Some pilots tape self regulating heating tape to the exterior of their tanks. I have used a heat lamp suspended inside the basket with an insulating cover over the basket. Overnight, this system gives me about 10 degrees F rise, as compared to outside temperature.
I’d like to place a heater in the basket. But I must consider the possibility of an inflammable environment. Most heating elements get red hot. That’s not good. My more serious concern is the thermostat. These often have contacts, which can spark, at a temperature to set off propane.
A flammable mixture of air/propane should not exist in the basket, but prudence suggests this is not a good assumption for design purposes. This is especially true as I heat my tanks outside a motel room.
My idea is to use one of the heated-oil electrical radiators found in hardware stores. The thermostat would be eliminated, replaced with a backed up electronic temperature sensor mechanism and electronics to power the heater through a solid state relay.
Reasonable temperatures can be achieved with no more than 500 watts. A 1500 watt heater in the basket is overkill.
I’d like other suggestions for this issue.
My hot air balloon feeds liquid, not gas, to the vaporizing coils of the burner. Heat loss from the balloon is about 1 million btu’s per hour. Our burners are rated for at least 12 million btu’s per hour. Burner output depends on fuel pressure. Propane fuel pressure is a function of fuel temperature. As fuel is burned off the pressure tends to drop and burner output drops. My burner requires a pressure of 60 to 140 psi. To achieve this pressure the fuel tanks need to be between 40 to 100 degrees F. Fuel temperature during winter flying can be an issue.
Some pilots tape self regulating heating tape to the exterior of their tanks. I have used a heat lamp suspended inside the basket with an insulating cover over the basket. Overnight, this system gives me about 10 degrees F rise, as compared to outside temperature.
I’d like to place a heater in the basket. But I must consider the possibility of an inflammable environment. Most heating elements get red hot. That’s not good. My more serious concern is the thermostat. These often have contacts, which can spark, at a temperature to set off propane.
A flammable mixture of air/propane should not exist in the basket, but prudence suggests this is not a good assumption for design purposes. This is especially true as I heat my tanks outside a motel room.
My idea is to use one of the heated-oil electrical radiators found in hardware stores. The thermostat would be eliminated, replaced with a backed up electronic temperature sensor mechanism and electronics to power the heater through a solid state relay.
Reasonable temperatures can be achieved with no more than 500 watts. A 1500 watt heater in the basket is overkill.
I’d like other suggestions for this issue.